Best effort multithreading cleanup version of os._exit()

[MarcM0]

Feature or enhancement + Pitch

I am looking for a way to shut down all threads that provides best effort cleanup. I understand that its not possible to guarantee cleanup since one of the threads might hang in the shutdown process. To address this, a timeout argument can be provided. You tell all the threads to cleanup. If they are not done by the timeout, you do what os._exit() does. This would help with error handling where you want to end a program and a clean shutdown is preferred, but not critical.

Previous discussion

Related to an old thread #77268