> The rails app is still limited by the GIL and, therefore, runs within a single process. Rails app-servers fork multiple OS processes to utilize all CPU cores

> The rails app is still limited by the GIL and, therefore, runs within a single process. Rails app-servers fork multiple OS processes to utilize all CPU cores despite the GIL. If you define a 'Rails app' as a single un-forked OS process (a definition I've never heard before) then yes, tautologically, a 'Rails app' could not utilize all CPU cores because of the GIL.