Which one should I start first rails server or sidekiq?

I know this is simple question to most of you. What after googling so many sites for sidekiq uninitialized constant error, i found few answers. like

1. Upgrade sidekiq version.
2. Eager Load your lib or job folder.
3. use after commit.
4. Restart Sidekiq.

After doing 1 ,2 & 3 , I am little bit confused because I am still getting the error. mperham in one issue said that Reloading is not thread-safe so Sidekiq can't use it. OTOH, Workers are designed to be very easy to TDD. If you use TDD, you'll find you don't need to restart Sidekiq much at all.

But when I restarted sidekiq no success. I am little bit confused like should I start sidekiq first to eager load the active job class or should I start rails server and then sidekiq to eager load the active job class.

Which should I start first so that I don't get uninitialized constant error or RecordNotFound error? Thanks.