Re: gtk_label_set_text () BUG !?!?!?!?!??!?!?!??!!? ( N00b)

[Michael Ekstrand <mekstran scl ameslab gov>]

On Aug 9, 2006, at 8:04 PM, hm wrote:
>   I`m workin` on a chessgame project. I`m willing to use GLib  
> threads to make ticking clock visible in my GUI. Thread function  
> modifies ( by gtk_label_set_text () ) text in label, which`s  
> pointer is given as a parameter to Thread. The problem is, that  
> when the thread function is modyfying text, application slows down,  
> and after first modification of label it is impossible to do  
> anything. No reaction. If gtk_label_set_text () is removed,  
> everything is all right. Is it a bug ? or what ? any clue ?

It sounds like you're violating some cardinal principles of  
multithreaded GUI programming....

Rule #1 on multithreading GUI's: don't do it if you don't need to.   
Your timer can be updated using GTK's idle or timeout callbacks.

Rule #2: Only ever call the GUI system from one thread (your main  
thread).  This rule can be different on some platforms, but in  
general, and particularly with GTK, this is the rule.  In GTK you can  
call from other threads (I think) by wrapping calls in  
g_threads_enter/g_threads_leave pairs, but IMHO it'd be better to use  
those only to protect setting an idle callback so that your worker  
thread actually schedules the display update to happen in the main  
thread.  I'm evaluating adding a similar mechanism in my program so  
that some complex computations and network polling (using libraries  
not integrated w/ glib) can be run in separate threads.

Make sure you're following those rules, and then see what happens.   
I'm guessing the problem is caused by calling GTK from multiple threads.

- Michael