[systemd-devel] Regression in v209: SIGKILL sent immediately after SIGTERM

[Stef Walter]

This commit breaks cockpit orderly shutdown:

> commit 743970d2ea6d08aa7c7bff8220f6b7702f2b1db7
> Author: Lennart Poettering <lennart at poettering.net>
> Date:   Fri Feb 7 16:12:09 2014 +0100
>
>     core: one step back again, for nspawn we actually can't wait for
> cgroups running empty since systemd will get exactly zero
> notifications about it

The children of a cockpit login session all get SIGKILL immediately
after SIGTERM (less than a tenth of a second apart). cockpit-agent and
cockpit-session takes more than a tenth of a second to shutdown cleanly.

The easiest way to reproduce this here, is a system shutdown. Even the
'reboot' that started the system shutdown (executed via ssh) gets a
SIGKILL before it can exit().

Here's some output from a simple systemtap probe which demonstrates this:

https://github.com/cockpit-project/cockpit/issues/1155#issuecomment-55374240

Here you can see how a cockpit unit, its login session scope, unit file,
unit properties:

https://github.com/cockpit-project/cockpit/issues/1155#issuecomment-55381385

This commit was introduced in v209, so (for example) the problem is
present in Fedora 21. Reverting the commit resolves the problem.

Cheers,

Stef

[1] Downstream bug: https://bugzilla.redhat.com/show_bug.cgi?id=1141137