Assume that you install Microsoft SQL Server 2016 on a server that its memory size is very big. When you roll back a batch that updates a large amount of data, it will take a long time to finish.
Note If you restart the server, the rollback will finish in 1 hour.
This issue occurs because rollback operation holds lots of X locks on the database table. Thus the business operation on the table cannot be continued.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.