Wait, does Javascript have good multi-threading support? I dont think it does.

Worker threads[0]. If you don't follow Javascript it's not surprising you hadn't heard about it, it's pretty new. Node also, thanks to v8, pretty much outperforms Python.

[0]https://nodejs.org/api/worker_threads.html

worker threads don't share the parent's heap though, right? They can only share state through a binary channel. It's something, but pretty different from traditional pthreads.

They can use SharedArrayBuffers[0] which wrap shared memory or they can pass ArrayBuffers. Node may not have the shared arrays yet, but the browsers do.

[0]https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...

Python has multiprocessing.shared_memory[1] since 3.8 to share arrays between processes, which accomplishes the same thing and circumvents the GIL issue.

[1] https://docs.python.org/3/library/multiprocessing.shared_mem...