Comment by cryptonector

> Basically vfork do a "stop the world".

vfork() does NOT stop the world in many / most implementations. The ones that do stop the world do it because someone misunderstood the whole "vfork() stops the parent process" -- yes, it stops the parent process in a pre-threads world, but it doesn't have to stop any other threads but the one that called vfork(). Indeed, many implementations don't do that.

(Someone once tried to make NetBSD's vfork() stop the world because that's what the pre-threading man page said it does. I did my utter best to keep that from happening at the time, and it didn't then. Hopefully no one tried again later.)