Re: Multi-threading

["Douglas C. MacKenzie" <doug mobile-intelligence com>]

One issue to remember is that GTK is not thread safe.
You must use a semaphore to make sure each access 
to GTK is complete before another is allowed to start.

Doug

On Wed, 2006-04-05 at 14:00 -0500, Bob Caryl wrote:
> Greetings everyone:
> 
> Here I am with another of my stupid questions:  I am currently working 
> on an application whose purpose is to demonstrate an ability to 
> communicate with the credit card processing servers operated by British 
> Petroluem (BP) in this country.  One of the things I must do is "listen" 
> for "device requests" issued by their EPS device.  All these 
> communications are done via TCP/IP over a local lan.
> 
> Since these device requests can arrive on a particular port at any time, 
> I have set up a pthread type thread to establish a listening socket on 
> that port.  When this thread's call to accept() returns a good socket I 
> spawn another thread that is a one shot affair to receive the actual 
> request and deal with it.  It is in this second thread that I am running 
> into trouble.
> 
> What I want to do (for now) is take the actual message arriving from the 
> BP EPS and display it in a Gtk::TextView by inserting it into the 
> Gtk::TextBuffer associated with the view.  So, I have made the function 
> used to spawn the second thread a friend of my window class and I make 
> the call to Gtk::TextBuffer::insert in that second thread.  Here is 
> where the problems arise.  If I do a standard "wait for the main loop" 
> device e.g.
> 
> while(Gtk::Main::events_pending())
>     Gtk::Main::iteration();
> 
> I get the following stderr output:
> 
> GLib-ERROR **: file gmain.c: line 1898 (g_main_dispatch): assertion 
> failed: (source) aborting...
> Terminated with signal 6 (Aborted)
> 
> Can anyone give me a hint as to my error(s) here?  I am calling the 
> Gtk::Main methods from a thread twice removed from the one that actually 
> started that instance of Gtk::Main...  Perhaps should I use 
> Glib::ThreadPool rather than pthreads?
> 
> All comments will be greatly appreciated,
> 
> Bob Caryl
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