Stream security issues with PUMA (using multiple threads) and MRI / jruby

I understand the main problems of the general condition in a multithreaded environment - even when using MRI with GIL / GVL. But I'm curious if there are problems when considering MRI + Puma vs jruby + Puma (if Puma is configured to use multiple threads in both cases).

In addition, what are the critical sections related to the general state in the above cases, and how will it differ in programs that are not based on the principle of the request (for example, those that will use a web server such as Puma)?

Thank you for your time and attention; Any recommendations regarding good resources on these topics would also be greatly appreciated.