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