Hi all,
the following code will likely deadlocked, if I don't call
gdk_thread_leave() before pthread_join(), because:
from gtkfaq-5.html#ss5.2
> Callbacks from GTK+ (signals) are made within the GTK+ lock.
deadlock happnes:
- loop_thread is waiting on sleep()
- button is clicked and GDK_THREADS_ENTER() is called in
gdk_event_dispatch() for callback function.
- callback function calls pthread_join() and block itself to wait
loop_thread.
- loop_thread leaves sleep() and trys to GDK_THREADS_ENTER() but it's
already locked by callback function and block itself
- DEADLOCK!
My question is:
- Is it ok to call gdk_thread_leave() in call-back function, if the
function does not call any gtk functions?
- if not, what would be the bast way to join threads within call back
function?
thanks in advance.
regards,
--
yashi
------- 8< -------- cut --------- 8< ---------
#include <stdio.h>
#include <unistd.h>
#include <pthread.h>
#include <gtk/gtk.h>
pthread_t thread;
int loop_going;
GtkWidget *window;
void *loop_thread(void *arg){
while(loop_going){
sleep(1);
GDK_THREADS_ENTER(); /* deadlock happens here */
gtk_widget_draw(window, NULL);/* nothing */
GDK_THREADS_LEAVE();
}
return NULL;
}
void loop_thread_start(){
loop_going = 1;
pthread_create(&thread, NULL, loop_thread, NULL);
}
void loop_thread_stop(){
loop_going = 0;
pthread_join(thread, NULL);
}
void quit(GtkWidget *widget, gpointer data){
/* GDK_THREADS_LEAVE();*/ /* uncomment these to work around the deadlock*/
loop_thread_stop();
/* GDK_THREADS_ENTER();*/
gtk_main_quit();
}
int main(int argc, char **argv){
GtkWidget *button;
g_thread_init(NULL);
gtk_init(&argc, &argv);
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
button = gtk_button_new_with_label("close");
gtk_signal_connect(GTK_OBJECT(button), "clicked", GTK_SIGNAL_FUNC(quit), NULL);
gtk_container_add(GTK_CONTAINER(window), button);
gtk_widget_show_all(window);
loop_thread_start();
GDK_THREADS_ENTER();
gtk_main();
GDK_THREADS_LEAVE();
}
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