It’s not limiting itself per se but each sidekiq worker will process one job at a time, so if you have 22000 emails waiting to go out seven of them will be processed at once.
On the ridiculous side of things, the server probably won’t be able to keep up if you set the number to 1000 parallel workers. So it’s about finding a number that suits all of your needs:
- process as many jobs as possible at the same time to get through the 22000 emails faster
- but don’t take up ALL of the server resources which would leave none left for users of the site