[systemd-devel] [PATCH] Avoid reloading services when shutting down

[Martin Pitt]

Lennart Poettering [2015-02-03 18:10 +0100]:
> I am very strongly against adding hacky work-arounds like this to PID

Yeah, indeed. This is why I asked for a more elegant approach, and
indeed the --no-block or --job-mode=ignore-dependencies sound like
slightly better approaches to this. I'll test these more thoroughly
tomorrow, thanks for pointing out!

> 1. The deadlocks are deadlocks, and implying --no-block if we are in
> shutdown mode is a pretty drastic hack I think that special cases one
> peculiar case way too much.

Right, the problem is of course more generic. Any set of jobs (i. e. a
transaction) which causes (maybe through some indirection) one of its
job members to get restarted/reloaded will suffer from this deadlock
problem, AFAIUI. Booting and shutdown are therefore mostly affected by
this as pretty much every other time there the pending transactions
are only very small.

> My recommendation would be to stick this into your /usr/bin/service
> compat glue. Use the state string "systemctl is-system-running"
> outputs to check if you are shutting down. If so, add --no-block to
> the params you pass to systemctl.

That actually sounds like just what's needed here. is-system-running
will also neatly cover the corresponding case on bootup.

> Another option might be to pass --job-mode=ignore-dependencies instead
> of --no-block, which was created for usecases like this, even though
> it is frickin' ugly...

For reload that should be fairly okay, as reload will quickly fail if
the unit isn't actually running, and if it is running its dependencies
already ought to be satisfied.

I'll look into both, thanks for the hints!

Martin
-- 
Martin Pitt                        | http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)