So yeah, I'm creating a programming language. And the language allows multiple threads. But, all threads are synchronized with a global interpreter lock, which means only one thread is allowed to execute at a time. The only way to get the threads to switch off is to explicitly tell the current thread to wait, which allows another thread to execute.

Parallel processing is of course possible by spawning multiple processes, but the variables and objects in one process cannot be accessed from another. However the language does have a fairly efficient IPC interface for communicating between processes.

My question is: Would there ever be a reason to have multiple, unsynchronized threads within a single process (thus circumventing the GIL)? Why not just put thread.wait() statements in key positions in the program logic (presuming thread.wait() isn't a CPU hog, of course)?

I understand that certain other languages that use a GIL have processor scheduling issues (cough Python), but they have all been resolved.