[Lazarus] GTK2 threading

[Anton Kavalenka]

On 22.01.2013 21:11, zeljko wrote:
> On Tuesday 22 of January 2013 19:04:43 Anton Kavalenka wrote:
>> On 22.01.2013 20:56, zeljko wrote:
>>> On Tuesday 22 of January 2013 18:52:31 Anton Kavalenka wrote:
>>>> Dear Lazarus developers!
>>>>
>>>> I'm examining the problem disturbing me for years.
>>>>
>>>> GTK2 applications provide thread-safety using internal mutexes passed
>>>> through gdk_thread_init()
>>>> And it works.
>>>>
>>>> Pure X-Applcation does so (orders X-messages per-thread) using
>>>> XInitThreads at early start of application.
>>>> And it also works
>>>>
>>>> But GTK Widgetset uses pure Xlib calls for determining keyboard states.
>>>> Xlib thread-safety is not initialized in GTK2 widgetset.
>>>>
>>>> IMO the problem half-way to resolve - either not use Xlib calls (pure
>>>> GTK2,3 - it is threadsafe) or make GTK and Xlib interoperable.
>>>> Or block GTK calls until Xlib call returned.
>>> Feel free to provide patch.
>>>
>>> zeljko
>> I'd like to, but i'm not a great expert in X - so i've subscribed to the
>> list to discuss.
>>
>> using XinitThreads at start of the program blocks GTK painting.
>> Forms are shown, but no text output.
>>
>> So - no way to alter XLib internals. The only way - to initialize GTK
>> threading in a way compatibel with X.
> So no way to use critical sections while calling xlib directly ?
> Can you open an issue and attach example ?
>
> z.
>
http://www.remlab.net/op/xlib.shtml

They say - there is a way

Xlib provides two groups of functions for multi-thread use:

    /* Thread-safety for global data */
    Status XInitThreads(void);

    /* Thread-safety for an individual display */
    void XLockDisplay(Display *display);
    void XUnlockDisplay(Display *display);

GNOMErs blame Xlib
https://mail.gnome.org/archives/gtk-list/2007-November/msg00122.html

I'll try to provide example.

Actually GUI does not need the multhreading.
But rendering into TBimap invokes Xlib calls as side effects.
So no way to compose off-screen.

regards,
Anton




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