[systemd-devel] "sshd.socket failed to queue socket startup job"

[Zbigniew Jędrzejewski-Szmek]

Hi,
I wanted to see what happens when using per-connection sshd at .service
from http://0pointer.de/public/systemd-units/sshd@.service.

After doing some ~1200 ssh connections, the socket went into
disabled state:
Feb 23 15:43:23 fedora systemd[1]: sshd.socket failed to queue socket startup job: File exists
Feb 23 15:43:23 fedora systemd[1]: Unit sshd.socket entered failed state.

After 'systemctl restart sshd.socket' connections work again.
Is this expected?

Another problem is resource usage:
after 7000 connections the RSS of systemd is up at 90MB. It started around 20MB,
so this gives 70 MB / 7000 connections = 10kB per connection, which is not bad,
but basically opens up a way to bring the machine down if the number of connection
is not limited in some other way.

Should systemd implement dropping old inactive template-generated units?
Or maybe does it do this already?

Thanks,
Zbyszek