When you install/remove an Emby plugin do not use the button in the restart notification that pops up in the Emby UI. Use the restart button on the Settings panel of the plugin.
If you do click on the restart button in the UI you will get a stuck pid. The internal button to the UI does not know to call the restart function of the emby init script.
To fix a stuck pid in command line:
cd /var/run/emby
rm emby.pid
Then go into process list in the web gui in Diagnostics / System Information
Look for the User Emby in the list and it's PID number then go back into command line:
kill # (whatever the PID number is)
service emby start
I put a message into Luke on this. We see what he says. But if you make sure to use the plugin Settings panel Restart button you will not have this issue.