Yeah, native code can block, and in those cases requires additional checks in that exposed native code. That runs into all the usual multithreading headaches,

Yeah, native code can block, and in those cases requires additional checks in that exposed native code. That runs into all the usual multithreading headaches, and depends on exactly which functions have been exposed to the lua interpreter. The advantage to this method over longjmp is that the function call is still valid and can be resumed at any point.