Re: Concurrent processes

[Hal Greenwald <hgreenwald itd nrl navy mil>]

Paul,
   My experience has been that it is a big mistake to distribute
GTK calls (or any X based widget set for that matter) among threads.
I use use multi-threading, however the gui controls live in a single
thread.
Hal

At 05:48 PM 4/3/01 -0400, Paul Davis wrote:
> >Is there a way to let me change parameters ? Maybe lookup signals or
> >somenthing like that ? I've heard something about threads but I don't
> >know what it is.... I'm really a newbie so if someone could give me some
> >very detailled way to do this, it would be very nice.
>
> nobody is going to give you a detailed enough account without simply
> pointing you at source code.
>
> a thread is bit like a process, except that instead of being an
> entirely separate program with its own protected virtual memory, it
> runs with complete access to the memory of the thread in which it was
> started. when you start a new process, you can't share data without
> specific arrangements to do so. when you start a new thread, all data
> is shared between all the threads in the process. the different
> threads all run "concurrently", where "concurrently" means
> time-sharing however many processors your system has with any other
> threads in any other processes that are ready to run.
>
> you can start by reading up on the pthreads library. then, from
> handler for the adjustment->changed signal, you can do this:
>
>         void *my_computationally_intensive_thread (void *arg)
>         {
>                 ... do the stuff you want here ...
>         }
>
>         gint
>         adjustment_changed_handler (GtkWidget *widget)
>         {
>             pthread_t thread_id;
>
>             pthread_create (&thread_id, NULL,
>                             my_computationally_intensive_thread,
>                             0);
>             pthread_detach (thread_id);
>
>             return TRUE;
>         }
>
> Thats just the bare bones. You'll no doubt need some mutexes to
> prevent various bad things from happening, and you should almost
> certainly make no calls to GTK or GDK from the separate thread. If you
> plan to do that, there's a bit more work you need to do.
>
> I happen to like a book called "Programming With Threads" by Kleiman
> et al. but there are many others on the topic floating around.
>
> --p
>
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