Comment by vlovich123
1 day ago
The paper explicitly covers it that various memory COW/snapshot mechanisms are probably faster and safer than the zygote pattern. As it stands getting the zygote pattern correct and safe is something you have to plan for upfront. You can’t retrofit it which is why the paper mentions it has poor composability. Also the advantages of the zygote pattern can be overstated since the memory sharing benefit is minimal since it has to happen so early and modern OSes already transparently CoW duplicate pages in the background.
In what sense can you not retrofit the zygote pattern?
I recommend at least skimming the paper as it covers this. But essentially you can’t just inject a call at a random point in code to start being a zygote. It’s something you have to plan up front as to the exact point you’re going to fork and that you’re going to do it at the start of program before any threads have started or any files are open and before any locks have been acquired. It’s basically all the challenges of invoking fork at arbitrary points in time.
The reason to do a zygote in the first place could be solved with alternative special APIs that are safer and harder to misuse. But we have fork so there’s not as big of a demand despite the warts.
Sure, but you can always retrofit a program to fork early on... this is a relatively trivial change. No?