[systemd-devel] Many user slices created and user managers spawned on boot

[Simon McVittie]

On Sat, 26 Jan 2019 at 10:26:23 -0600, Steve Bergman wrote:
> possibly since before the upgrade from Debian 7 with sysvinit to
> Debian 9 with systemd

I hope you upgraded from Debian 7 (usually booted with sysvinit) to Debian 8
(usually booted with systemd), then rebooted, cleaned up any obsolete packages,
and upgraded from Debian 8 to Debian 9 as a separate step. Debian does not
support upgrades that skip a release: our releases are about 2 years apart, and
applying 4 or more years of development to a running system is too much change
to do reliably in one go. If this system is working, it's probably fine now,
but please upgrade in 1-release steps if you upgrade any similar systems.

The major "Debianism" to be aware of with systemd is that in upstream
systemd, logind's [Login] KillUserProcesses option defaults to "yes",
whereas in Debian it defaults to "no".

The benefit of that change is that on Debian systems, tools like screen(1) and
tmux(1) work as intended without needing special steps to exclude them from the
session scope; the cost is that processes that continue to run after a user's
session has ended are not cleaned up (because systemd can't know that they
weren't meant to behave like screen or tmux).

    smcv