bug#30290: guix-daemon slows to a crawl when a substitute server is offline

[zimoun]

Hi,

On Mon, 29 Jan 2018 at 22:07, Maxim Cournoyer <maxim.cournoyer@gmail.com> wrote:
> When a substitute server used by guix-daemon is offline, the daemon will
> keep attempting to connect to it, even when it shouldn't need any data
> (ran 'sudo guix system reconfigure my-config.scm' multiple times in a
> row.
>
> With the disconnected server (bayfront in my case), that command would
> take close to 8 minutes, with many system calls like:
>
> connect(14, {sa_family=AF_INET, sin_port=htons(443), 
> sin_addr=inet_addr("141.255.128.56")}, 16) = -1 EINPROGRESS
>
> which wasted 5 seconds each time.
>
> After removing this server from my substitute servers list, the same
> operation (system reconfigure) is 8 times faster (1 minute).
>
> Suggestion: the daemon should stop trying to use the offline substitute
> server after trying for X times, and print a warning about it.

What is the status of this bug?  Especially with the recent additions in
Cuirass?

Is it still an issue?  Is some timeout still happening?

Well, in summary, the 3 relevant messages are:

-------------------- Start of forwarded message --------------------
From: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Date: Fri, 18 Dec 2020 22:04:04 -0500

I'm not sure if the recent offloading work that Mathieu did touched that
topic.  I'd need to test the scenario.  Perhaps a system test would be
useful.
-------------------- End of forwarded message --------------------

-------------------- Start of forwarded message --------------------
From: Ludovic Courtès <ludo@gnu.org>
Date: Tue, 22 Dec 2020 16:16:08 +0100

Is it still a problem?  Commit 4f5234be0378368e6af25925db46612838d25e58
(Nov. 2019) added a table of unreachable hosts.  That way, a ‘guix
substitute --query’ process won’t retry connections to an unreachable
host.
-------------------- End of forwarded message --------------------

-------------------- Start of forwarded message --------------------
Date: Mon, 28 Dec 2020 14:19:02 +0200
From: Efraim Flashner <efraim@flashner.co.il>

Occasionally my internet drops itself, and I find I'm left forever
waiting for a timeout to see what sources I have cached locally.
-------------------- End of forwarded message --------------------


Cheers,
simon