how to shrink(and also reduce size on disk) a very big log file in SQL server 2016
I completely agree with Biju, I had similar case when log size was not reducing at all however this was in Sybase, nevertheless concept is same, you may refer the case here:

Database Backup size not reducing 

You can also use sp_WhoIsActive to check what is currently running at your database and what is the underlying command, who is running it, from how long this is running and many other details; this would help you in finding whether you should kill the specified spid or should consult with user before taking any action. I hope this should help.