> it seems like you would need some runtime mechanism in the child to coordinate this I had been thinking about what mechanism you could put in place to coordi

> it seems like you would need some runtime mechanism in the child to coordinate this I had been thinking about what mechanism you could put in place to coordinate, but you made me realize that if your language provides some kind of event loop, then that would be the right place to have the "please stop while I push this old function under the rug" functionality. And languages that have async/await have to have such a runtime, which can make the whole thing completely transparent to the programmer. But you still need the inter-process comms to let the runtime know it should wait for a bit, so your last sentence still applies: at that point have the process rewrite itself.