Bug#1064982: gnuplot-qt: gnuplot displays a window with nothing in it

[Vincent Lefevre]

On 2024-02-29 12:34:17 +0100, Vincent Lefevre wrote:
> Indeed, this was caused by the upgrade of the pango library. I've
> just posted on the upstream bug:
> 
> Actually, the problem also occurs with gnuplot 5. It has actually
> appeared with the 1.52 pango library: downgrading the pango packages
> to 1.51 makes the problem disappear, both with gnuplot 5 and 6. Now,
> I don't know whether this is a bug in pango or a bug in gnuplot that
> is triggered only with the new version of pango (for instance, it
> might be possible that pango 1.52 is faster than 1.51, making the
> problem appear, since it seems to be a race condition).

I've identified the "problematic" commit in Pango, and I would tend
to say that this is the reason:

https://gitlab.gnome.org/GNOME/pango/-/commit/89442dae443eba2aa0f0a526b4d6d39c0c9b13c6

According to the commit message, a new thread was created "for every
single fontconfig call". Now "a single fontconfig thread per fontmap"
is used. So I suppose that this makes Pango faster, triggering the
race condition in gnuplot.

I've updated the upstream gnuplot bug and opened a bug in Pango,
hoping confirmation:

https://gitlab.gnome.org/GNOME/pango/-/issues/784

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Vincent Lefèvre <vincent at vinc17.net> - Web: <https://www.vinc17.net/>
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