This is not really a new thing but maybe it's not well known.
Ruby's had aysnc IO support for at at least 10 years I think.
Rails itself has been using Concurrent Ruby since at least Rails 5 but I think it had its own concurrency patterns even before that. e.g. ActiveRecord database drivers.
Jesse Storimer's Working with Ruby Threads book from 2013 is still a really good resource for concurrency in ruby.
