[Nix-dev] Delays on ssh connection

[emil.rangden at chas.se]

On 2015-02-11 9:57, Carles Pagès wrote:
> Hi all,
> 
> My system (nixos 14.12.231.139ead2) is in a state that, when
> connecting through ssh there is a delay of ~30s. It happened to me a
> while ago and was 'solved' with a reboot.
> 
> Looking at the logs, I see:
> feb 10 09:33:03 pica sshd[9346]: pam_unix(sshd:session): session
> opened for user xxx by (uid=0)
> feb 10 09:33:03 pica systemd-logind[1748]: New session 66 of user xxx.
> feb 10 09:33:28 pica sshd[9346]: pam_systemd(sshd:session): Failed to
> create session: Connection timed out
> 
> Also, the log is full of:
> feb 10 09:33:04 pica systemd[1]: Looping too fast. Throttling
> execution a little.
> 
> Seems like there is something wrong with systemd. Trying to look for
> an explanation, I've found people commenting on similar issues that
> were triggered by systemd crashes, but not exactly what I see.
> 
> Going back in the log, the 'throttling' starts to appear after this:
> feb 09 02:15:01 pica
> /nix/store/8xg2yyyj651nik95lqmwza4xn0h7d7na-cron-4.1/bin/cron[24928]:
> (root) CMD (/nix/store/8iq0r1d7na-cron-4.1/bin/cron[24928]: (root) CMD
> (/nix/store/8iq0r1l97dzcsvkv33zg465gxlsx56dl-systemd-217/bin/systemctl
> start ul97dzcsvkv33zg465gxlsx56dl-systemd-217/bin/systemctl start
> update-locatedb.service)
> 
> Though there's previous executions of that cron task that didn't
> trigger the issue.
> 
> Any clues on what might be wrong and/or how to solve this?
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Might not at all be what you are looking for, but I had a similar 
problem
with nixos-containers. It was 'solved' by telling sshd not to do any dns
lookups with something like

   services = {
     openssh = {
       enable = true;
       extraConfig =
         ''
           UseDNS no
         '';
   };