Vladimir wrote: > I'm writing program with several threads each of which uses gtk. > I need to wait for one of the threads in gtk-generated callback. I can't do > it directly because of gdk lock. So the question is: can I temporarily > release gdk lock in gtk-generated callback ? Will it cause any problems ?
You should know that accessing GDK / GTK+ functions from different threads is bad programming practice, because GTK+ is not thread-safe. Trying to compensate this properly on application side (using gdk_threads_enter() + gdk_threads_leave() ) would result in quite some code overhead, likely some performance penalty and is error-prone. Even worse sounds the idea of "waiting for something" inside a GTK+ callback. They are supposed to finish as quickly as possible. Everything else sounds like great potential for deadlocks. So the answer is: no. Even if your app doesn't crash immediately, it may do so sometime later in arbitrary states, possibly leaving you with no trace where to search for the cause of the crash. Generally, the better way would likely be, to set a global flag when the thread you want to wait for, finishes. A GTK+ handler must not wait for this, but rather be able to deal with both situations appropriately: either the other thread hasn't finished yet, then exit immediately. If the other thread has finished, then do what you originally wanted to. If your handler is not supposed to be executed at all before the other thread has finished, then you should prevent the handler to be called, rather than attempting to wait within the handler until the other thread finishes. You know, there are multiple options for preventing handlers to be executed. You're free to use multiple threads for arbitrary computations within your program. But you really should not access GTK+ / GDK from within each of them. It makes programming more complicated and error-prone and the graphics output a bit slower (due to all the thread locks that need to be provided). Leaving all the GDK / GTK+ stuff to just one thread would definitely be the better idea. Since you started with programming multiple threads you should also know how to signal a central GTK+ / GDK thread what to do from other threads, don't you? _______________________________________________ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
