[cyberax]

> My trick for that is that the set of threads that I create pre fork have to be suspendable and resumable

Well, yes. You need to wait for all the threads to park themselves at safepoints. This can work if you control the whole runtime, and you don't use something that creates threads behind your back.

This is actually why I've always been interested in a better fork(), it has a lot of parallels with stop-the-world needed for GCs.

> Folks have been saying that it's terrible for as long as I can remember. But it's still there, because it's better than the alternatives

I don't think we have alternatives? Except maybe ptrace()?