Re: Re: GTK threads and socket operations

[Emmanuele Bassi <ebassi gmail com>]

hi;

On 26 November 2014 at 10:27, Sergei Naumov <vomus rambler ru> wrote:
> Is there any tutorial on them? I searched the Web and did not find any good
> tutorial on GTK threads.

the only tutorial needed is probably something like:

  Q: Can I use GTK API from different threads?
  A: No.

if you have a long-running operation in a thread, you need to schedule
UI updates in the same main context used by GTK — i.e. use
g_timeout_add(), g_idle_add(), or g_main_context_invoke() to schedule
a function call from your thread, and pass the data needed to update
the UI to that function.

ciao,
 Emmanuele.

>  26.11.2014, 12:41:16 пользователь Bernhard Schuster
>  (schuster bernhard gmail com) написал:
>
>
>
>  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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