Lua itself doesn't have threads that run concurrently, what it has is coroutines, that is a form of cooperative multitasking - you manage when to yield. Hovewer, most common type of thread implementation is mutexing Lua state, and it is equivalent to GIL. You are better to run multiple Lua states (that communicate via host code) concurrently rather running your threads in the same single Lua state.
Ilya Shchukin
