Comment 26 for bug 1707312

From systemd documentation:

"If set to control-group, all remaining processes in the control group of this unit will be killed on unit stop (for services: after the stop command is executed, as configured with ExecStop=)."

We don't want that. We want lighttpd to care about spawned fcgi processes (see fastcgi-php mod, if enabled, lighttpd spawns constant number of fcgi backends and stops them on exit). And only if it fails to stop them, we want to kill them after a timeout. That's exactly what "mixed" mode will do according to the documentation:

"If set to mixed, the SIGTERM signal (see below) is sent to the main process while the subsequent SIGKILL signal (see below) is sent to all remaining processes of the unit's control group."

If spawned fcgi processes will be terminated instantly when stop (restart, whatever) command is called, it will not be a graceful stop/restart.