bug#27780: guix environment to build guile from git required excessive CPU time

[Ludovic Courtès]

Hi Mark,

Mark H Weaver <address@hidden> skribis:

> I just ran the following command on my Thinkpad X200 running GuixSD:
>
>   ./pre-inst-env guix environment guile --ad-hoc autoconf automake libtool 
> flex gettext
>
> Using the guix client from a git checkout at v0.13.0-1496-gcfd6a3b1e,
> and using guix-daemon from guix-0.13.0-3.b547349.
>
> This command took approximately 20 minutes of CPU time before
> downloading anything except possibly some NARINFOs.  During this initial
> 20 minutes of CPU-bound activity, the only output was 4 occurrences of
> the following message:
>
> substitute: updating list of substitutes from 
> 'https://mirror.hydra.gnu.org'... 100.0%
>
> The CPU time was roughly evenly split between the following two
> processes:
>
> USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
> root      8456 57.0  0.1  37420  7788 ?        Rs   22:27  11:31  \_ 
> /gnu/store/gkv8zl774h2qpa89mrf6d74fry3rsnpa-guix-0.13.0-3.b547349/bin/guix-daemon
>  8450                guixbuild --max-silent-time 0 --timeout 0 
> --substitute-urls https://mirror.hydra.gnu.org --gc-keep-derivations=yes 
> --gc-keep-outputs=yes
> root      8457 45.0  0.9 124040 38556 ?        Rl   22:27   9:03      \_ 
> /gnu/store/z16li2znnk2pdgrg3ldm34k669pcrdcx-guile-2.2.2/bin/guile 
> --no-auto-compile 
> /gnu/store/gkv8zl774h2qpa89mrf6d74fry3rsnpa-guix-0.13.0-3.b547349/bin/.guix-real
>  substitute --query

Is it reproducible?  If/when that happens again, could you ‘strace’ the
‘guix substitute’ process?

Any idea whether hydra.gnu.org was loaded at the time and returning 504
(“Gateway Timeout”)?

Thanks,
Ludo’.