[scott_s]

However, the approach explained in this presentation does just that. The solution looks like a crude process operating systems scheduler.

[kingkilr]

It's not really, it's simply threads asking the main thread to drop every 5 ms, and then relying on the OS to schedule them. If Python had it's own scheduler it would do things like assigning priorities and actually deciding which thread would take over when the GIL was dropped.