bug#44053: ‘xdg-mime-database’ profile hook is slow

["Ludovic Courtès" <ludo@gnu.org>]

Hi,

Luis Felipe <luis.felipe.la@protonmail.com> skribis:

> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
> On Tuesday, November 3, 2020 11:32 PM, zimoun <zimon.toutoune@gmail.com> wrote:
>
>> Hi,
>>
>> > https://git.savannah.gnu.org/cgit/guix.git/commit/?id=76ea70bd70aeb76570445c11cea2f98139192b54
>>
>> Clever workaround! What are now the performances on previous examples
>> (same profiles and same packages)?
>
> In my case there seem to be no improvement (using Guix 5e7cf66fb35780f930ad0bc5fe21ac330df4411d).

Please note that the change above addresses only one specific source of
slowness, the ‘xdg-mime-database’ hook, and only in specific cases.

It’s good to look at the overall timing of ‘guix install’, because
that’s what matters in the end, but as we work on optimizing it, we have
to look at specific aspects of it.

> $ time guix package -i perl --max-jobs=1

[...]

> injertando 12 paquetes en /gnu/store/anknpdyhmfirw3rz2k9zm9kiyak8yy1s-cups-filters-1.27.4.drv ...
> construyendo la base de datos MIME XDG...
> injertando 3 paquetes en /gnu/store/xgny7xbl635g8na8x03x4cdr7abiphiw-cups-2.3.3.drv ...
> injertando 20 paquetes en /gnu/store/yhjl68x7kcjbv40v823x4hl8rvv8l50b-gtk+-2.24.32.drv ...
> injertando 21 paquetes en /gnu/store/kq37fnw8335f1hqc3j4hhqqcdnhl371p-gtk+-3.24.20.drv ...
> creando la caché de temas de iconos de GTK+...
> construyendo los ficheros de caché para los métodos de entrada de GTK+...
> construyendo perfil con 86 paquetes...
>
>
> real	8m38,121s
> user	0m2,742s
> sys	0m0,338s

Here it’s likely that grafting is what’s taking the most time on a
spinning disk.

We should hack (guix status) so it can optionally prefix each event with
a timestamp.

As far as ‘xdg-mime-database’ is concerned, it should be down to 0s,
unless your profile contains one of the packages I cited (libreoffice,
gcr, hugin, etc.).

Thanks,
Ludo’.