Re: GTK threads and socket operations

[Bernhard Schuster <schuster bernhard gmail com>]

You modify your label from a thread that is not the main/ui thread.
Gtk+ is not threadsafe (few exceptions). Use g_idle_add/ g_timeout_add/ and
friends (those are threadsafe) to implicitly serialize your ui
modifications into the gtk mainloop.

Do not use GDK_THREADS_ENTER/LEAVE foo unless you are maintaining a legacy
codebase and you know exactly what this means including its implications.

Best

Bernhard
On Nov 26, 2014 9:02 AM, "Sergei Naumov" <vomus rambler ru> wrote:

> Hi!
>
> I am writing an application that periodically reads data from network
> sockets
> (from Modbus enabled devices actually) and displays them in GTK+
> application. I
> read some tutorials about GTK threads and created a separate thread that
> encompasses Modbus reads and updates to GTK labels:
>
> modbus_thread = g_thread_new ("update_from_modbus",update_
> from_modbus,NULL);
>
> The update_from_modbus() has a bunch of socket reads (inside
> xantrex_read_value())
> and gtk_label_set_text()
>
> sprintf(params_val_text,"%-5.1f (%4.1f Hz)\n%-4.1f\n%-4d",
> 0.001*xantrex_read_value(modbus_pointer,0x004C,RECONSTRUCT_YES),
> 0.01*xantrex_read_value(modbus_pointer,0x004E,RECONSTRUCT_YES),
> 0.001*xantrex_read_value(modbus_pointer,0x0054,RECONSTRUCT_YES),
> xantrex_read_value(modbus_pointer,0x0052,RECONSTRUCT_YES));
> gtk_label_set_text (GTK_LABEL(ac1_params_val),params_val_text);
> gtk_label_set_justify(GTK_LABEL(ac1_params_val),GTK_JUSTIFY_LEFT);
>
> However after several hours I see crashes when the program tries to
> reconnect to
> my device. I tried to enclose GTK operations into gtk_threads_enter() /
> gtk_threads_leave() but it has no effect. Can anyone, please explain what
> is
> wrong here or may be point to a good example of multithreaded GTK code
> which has
> network socket operations in it?
>
> Thanks in advance,
>
> -- Sergei
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