Re: systemd's connections to /run/systemd/private ?

[Brian Reichert <reichert@xxxxxxxxxxx>]

On Wed, Jul 10, 2019 at 10:44:14PM +0000, Zbigniew J??drzejewski-Szmek wrote:
> That's ancient... 228 was released almost four years ago.

That's the joy of using a commercial Linux distribution; they tend
to be conservative about updates.  SLES may very well have backported
fixes to the packaged version they maintain.

They may also have a newer version of a systemd RPM for us to take.

I'm looking for an efficient way to repro the symptoms, as to confirm
whether a newer RPM solves this for us.

> > > > When we first spin up a new SLES12 host with our custom services,
> > > > the number of connections to /run/systemd/private numbers in the
> > > > mere hundreds. 
> > 
> > > That sounds wrong already. Please figure out what those connections
> > > are. I'm afraid that you might have to do some debugging on your
> > > own, since this issue doesn't seem easily reproducible.

Above, I cite a desire for reproducing the symptoms.  If you're
confident that a newly-spun-up idle host should not hover at hundreds
of connections, then hypothetically I could update the vendor-provided
systemd RPM (if there is one), reboot, and see if the connection
count is reduced.

> strace -p1 -e recvmsg,close,accept4,getsockname,getsockopt,sendmsg -s999
>
> yields the relevant info. In particular, the pid, uid, and guid of the
> remote is shown. My approach would be to log this to some file, and
> then see which fds remain, and then look up this fd in the log.
> The recvmsg calls contain the serialized dbus calls, a bit messy but
> understandable. E.g. 'systemctl show systemd-udevd' gives something
> like this:

Thanks for such succinct feedback; I'll see what I can get from this.

In my prior email, I showed how some of the connections were
hours/days old, even with no connecting peer.

Does that sound like expected behavior?

> HTH,
> Zbyszek

-- 
Brian Reichert				<reichert@xxxxxxxxxxx>
BSD admin/developer at large	
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