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

[zimoun]

Hi,


On Wed, 24 Mar 2021 at 22:55, zimoun <zimon.toutoune@gmail.com> wrote:
> 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.

[...]

> From: Maxim Cournoyer <maxim.cournoyer@gmail.com>
> Date: Fri, 18 Dec 2020 22:04:04 -0500 (24 weeks, 4 days, 18 hours ago)
>
> 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.
> ----------
>
> From: Ludovic Courtès <ludo@gnu.org>
> Date: Tue, 22 Dec 2020 16:16:08 +0100
> Date: Tue, 22 Dec 2020 16:16:08 +0100 (24 weeks, 1 day, 6 hours ago)
>
> 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.
> ----------
>
> From: Efraim Flashner <efraim@flashner.co.il>
> Date: Mon, 28 Dec 2020 14:19:02 +0200
> Date: Mon, 28 Dec 2020 14:19:02 +0200 (23 weeks, 2 days, 9 hours ago)
>
> Occasionally my internet drops itself, and I find I'm left forever
> waiting for a timeout to see what sources I have cached locally.
> ----------

What is the current stats of this bug?   Is it still happening with the
recent improvements of Cuirass?

Cheers,
simon