gnome_show_url() hangs in threaded programs

[Pawel Salek <pawsa theochem kth se>]

Hi,

I have impression that something has got broken in gnome_show_url() and
related functions (or perhaps, a bug has surfaced that has not been active
earlier).

Basically, if you start any thread in your program (you can detach it or
not, join it or keep it running), gnome_show_url() will hang (tested with
gnome-libs-1.2.13). I paste below short program demonstrating it. I see two
possibilities: either this program or gnome-libs contain a bug. The program
is so simple that there is hardly a place for a bug (prove me wrong).

Any ideas?

Pawel
-- 
-----
Pawel Salek, pawsa theochem kth se
--------- cut here ----------------------------------
/* Pawel Salek, pawsa theochem kth se, 2001-08-22
   Program demonstrating bug in gnome_url_show() and related functions.
   Basically, gnome_url_show() will hang when the program creates ANY
thread 
   (no matter if the thread has been detached, joined, or contiunes 
   execution).

   Wrong behavior observed with: gnome-libs-1.2.13-7
   Correct (no hang) behavior observed with: 
   COMPILE with:
   cc `gnome-config --cflags gnome` url-test.c \
   `gnome-config --libs gnomeui` -lgthread -o url-test
   EXECUTE:
   ./url-test
   no thread is created. Clicking on the button brings up given page.
   ./url-test n
   a thread is created and joined. Clicking on the button hangs the
program.
   ./url-test f
   a thread is created and joined. A fork handlers are registered.
   Clicking on the button hangs the program. The fork handlers are not
   executed.
*/


#include <gnome.h>
#include <pthread.h>

#define PACKAGE "url-test"
#define VERSION "1.0.0"

void*
my_thread(void* data)
{
  printf("my_thread.\n");
}

void
press_cb(GtkWidget* w, const char* url)
{
  printf("press_cb\n");
  /* ERROR 1: This never exececutes the browser - and never returns
   * when there was at least one extra thread running. */
  gdk_threads_leave();
  gnome_url_show(url);
  gdk_threads_enter();
}

void
unlock_parent()
{
  printf("Unlocking parent\n");
}

void
unlock_child()
{
  printf("Unlocking child\n");
}

int main(int argc, char* argv[])
{
  const static char* the_url = "http://www.redhat.com/";;
  GtkWidget* window, * button;
  pthread_t open_thread;
  void* ret;

  printf("gnomepthread tester. Give any parameter and a thread will be
run.\n"
         "If the parameter begins with letter 'f', fork handlers will be "
         "installed.\n");
  g_thread_init(NULL);
  gnome_init(PACKAGE, VERSION, argc, argv);

  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  button = gtk_button_new_with_label(the_url);
  gtk_signal_connect(GTK_OBJECT(button), "pressed", press_cb,
                     (gpointer)the_url);
  gtk_signal_connect(GTK_OBJECT(window), "delete_event", gtk_main_quit,
NULL);
  gtk_container_add(GTK_CONTAINER(window), button);
  gtk_widget_show_all(window);

  if(argc>1) {
    /* ERROR 2: the registered functions are never executed. */
    if(*argv[1] == 'f') {
      pthread_atfork(NULL, unlock_parent, unlock_child);
      printf("Fork handlers installed.\n");
    }
    pthread_create(&open_thread, NULL, my_thread, NULL);
    pthread_join(open_thread, &ret);
    printf("thread started.. and joined. Continuing...\n");
  } else printf("Starting without any threads.\n");
  gdk_threads_enter();
  gtk_main();
  gdk_threads_leave();

  return 0;
}
----------- cut here -------------------------

/* Pawel Salek, pawsa theochem kth se, 2001-08-22
   Program demonstrating bug in gnome_url_show() and related functions.
   Basically, gnome_url_show() will hang when the program creates ANY thread 
   (no matter if the thread has been detached, joined, or contiunes 
   execution).

   Wrong behavior observed with: gnome-libs-1.2.13-7
   Correct (no hang) behavior observed with: 
   COMPILE with:
   cc `gnome-config --cflags gnome` url-test.c \
   `gnome-config --libs gnomeui` -lgthread -o url-test
   EXECUTE:
   ./url-test
   no thread is created. Clicking on the button brings up given page.
   ./url-test n
   a thread is created and joined. Clicking on the button hangs the program.
   ./url-test f
   a thread is created and joined. A fork handlers are registered.
   Clicking on the button hangs the program. The fork handlers are not
   executed.
*/


#include <gnome.h>
#include <pthread.h>

#define PACKAGE "url-test"
#define VERSION "1.0.0"

void*
my_thread(void* data)
{
  printf("my_thread.\n");
}

void
press_cb(GtkWidget* w, const char* url)
{
  printf("press_cb\n");
  /* ERROR 1: This never exececutes the browser - and never returns
   * when there was at least one extra thread running. */
  gdk_threads_leave();
  gnome_url_show(url);
  gdk_threads_enter();
}

void
unlock_parent()
{
  printf("Unlocking parent\n");
}

void
unlock_child()
{
  printf("Unlocking child\n");
}

int main(int argc, char* argv[])
{
  const static char* the_url = "http://www.redhat.com/";;
  GtkWidget* window, * button;
  pthread_t open_thread;
  void* ret;

  printf("gnomepthread tester. Give any parameter and a thread will be run.\n"
	 "If the parameter begins with letter 'f', fork handlers will be "
	 "installed.\n");
  g_thread_init(NULL);
  gnome_init(PACKAGE, VERSION, argc, argv);

  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  button = gtk_button_new_with_label(the_url);
  gtk_signal_connect(GTK_OBJECT(button), "pressed", press_cb,
		     (gpointer)the_url);
  gtk_signal_connect(GTK_OBJECT(window), "delete_event", gtk_main_quit, NULL);
  gtk_container_add(GTK_CONTAINER(window), button);
  gtk_widget_show_all(window);

  if(argc>1) {
    /* ERROR 2: the registered functions are never executed. */
    if(*argv[1] == 'f') {
      pthread_atfork(NULL, unlock_parent, unlock_child);
      printf("Fork handlers installed.\n");
    }
    pthread_create(&open_thread, NULL, my_thread, NULL);
    pthread_join(open_thread, &ret);
    printf("thread started.. and joined. Continuing...\n");
  } else printf("Starting without any threads.\n");
  gdk_threads_enter();
  gtk_main();
  gdk_threads_leave();

  return 0;
}