Can you realistically open thousands of fibers though ? You will hit the db connection limitation pretty soon no? I'm just wondering what was the end goal - do people hit maximum threads limitation and need fibers?
EDIT: I might be wrong here it could be that each Fiber released the connection when it's de-scheduled. I'd still like to get a grasp on how this improves performance ...
Do you mean DB connections for the DB server or some db connection limit in rails? For the DB server, you can scale that out horizontally so it doesn't have to be a hard limit if you need more connections.
Realistically I don't see any benefit at all. That's not to say it's a bad change, just not one that provides much of any real world benefit to a thread-based system like Sidekiq. I would love to be proven wrong though!
EDIT: I might be wrong here it could be that each Fiber released the connection when it's de-scheduled. I'd still like to get a grasp on how this improves performance ...