Bytecode vs JIT doesn't really make a difference. But taking to question to managed languages (so Python, Erlang, JS, Ruby, .NET, JVM etc) - there isn't really

Bytecode vs JIT doesn't really make a difference. But taking to question to managed languages (so Python, Erlang, JS, Ruby, .NET, JVM etc) - there isn't really a GIL problem to start with in language design, there's just design choices wrt what, if anything, to do about parallelism/concurrency. For example Erlang and recent browser Javascript skip shared memory parallelism and use message passing (JS web workers and Erlang processes). Python's approach is motivated by it's simple refcount-based garbage collection, other GCs have it easier.