Comment 3 for bug 1913736

It seems this will continue to leak processes every time that openvswitch-switch gets restarted. For example (and same details are in https://paste.ubuntu.com/p/jHs5SmZVPS/):

Note the message: Jan 29 13:54:30 juju-42c75d-zaza-ab85a8c30e4d-1 systemd[1]: ovn-host.service: Found left-over process 26159 (ovn-controller) in control group while starting unit. Ignoring.

● ovn-host.service - LSB: OVN host components
   Loaded: loaded (/etc/init.d/ovn-host; generated)
   Active: active (running) since Fri 2021-01-29 13:54:30 UTC; 12s ago
     Docs: man:systemd-sysv-generator(8)
  Process: 28042 ExecStop=/etc/init.d/ovn-host stop (code=exited, status=0/SUCCESS)
  Process: 28057 ExecStart=/etc/init.d/ovn-host start (code=exited, status=0/SUCCESS)
    Tasks: 15 (limit: 2361)
   CGroup: /system.slice/ovn-host.service
           ├─26158 ovn-controller: monitoring pid 26159 (healthy)
           ├─26159 ovn-controller unix:/var/run/openvswitch/db.sock -vconsole:emer -vsyslog:err -vfile:info --no-chdir --log-file=/var/log/openvswitch/ovn-controller.log --pidfile=/var/run/openvswitch/ovn-controller.pid --detach --monitor
           ├─27816 ovn-controller: monitoring pid 27817 (healthy)
           ├─27817 ovn-controller unix:/var/run/openvswitch/db.sock -vconsole:emer -vsyslog:err -vfile:info --no-chdir --log-file=/var/log/openvswitch/ovn-controller.log --pidfile=/var/run/openvswitch/ovn-controller.pid --detach --monitor
           ├─28073 ovn-controller: monitoring pid 28074 (healthy)
           └─28074 ovn-controller unix:/var/run/openvswitch/db.sock -vconsole:emer -vsyslog:err -vfile:info --no-chdir --log-file=/var/log/openvswitch/ovn-controller.log --pidfile=/var/run/openvswitch/ovn-controller.pid --detach --monitor

Jan 29 13:54:30 juju-42c75d-zaza-ab85a8c30e4d-1 systemd[1]: This usually indicates unclean termination of a previous run, or service implementation deficiencies.
Jan 29 13:54:30 juju-42c75d-zaza-ab85a8c30e4d-1 systemd[1]: ovn-host.service: Found left-over process 26159 (ovn-controller) in control group while starting unit. Ignoring.
Jan 29 13:54:30 juju-42c75d-zaza-ab85a8c30e4d-1 systemd[1]: This usually indicates unclean termination of a previous run, or service implementation deficiencies.
Jan 29 13:54:30 juju-42c75d-zaza-ab85a8c30e4d-1 systemd[1]: ovn-host.service: Found left-over process 27816 (monitor) in control group while starting unit. Ignoring.
Jan 29 13:54:30 juju-42c75d-zaza-ab85a8c30e4d-1 systemd[1]: This usually indicates unclean termination of a previous run, or service implementation deficiencies.
Jan 29 13:54:30 juju-42c75d-zaza-ab85a8c30e4d-1 systemd[1]: ovn-host.service: Found left-over process 27817 (ovn-controller) in control group while starting unit. Ignoring.
Jan 29 13:54:30 juju-42c75d-zaza-ab85a8c30e4d-1 systemd[1]: This usually indicates unclean termination of a previous run, or service implementation deficiencies.
Jan 29 13:54:30 juju-42c75d-zaza-ab85a8c30e4d-1 systemd[1]: Starting LSB: OVN host components...
Jan 29 13:54:30 juju-42c75d-zaza-ab85a8c30e4d-1 ovn-host[28057]: * Starting ovn-controller
Jan 29 13:54:30 juju-42c75d-zaza-ab85a8c30e4d-1 systemd[1]: Started LSB: OVN host components.