alt Hacker NewsThe zygote pattern[1] is a great optimization to deal with the cost of forking, but IMHO, being able to inexpensively spawn a carefully tailored process regardless of the size and scope of the current process would be better.
I would guess it would be a small difference in measurable performance between zygote and a direct clean spawn, but it's one less trick an application needs to do, and it would be very helpful for libraries that spawn things. Spawning inside a library isn't always a great thing to do, but some things would really benefit from process level isolation.
[1] In case one isn't aware, the zygote pattern involves forking a 'zygote' process during application startup, and having that process do any forks that need to happen during application runtime. This reduces the cost of forking in large applications, because the zygote will have few fds open and use little memory. This lets your large application spawn new processes without delaying the application or the startup of the new processes. Some applications will spawn many zygotes to allow parallelism for spawning at runtime.
Replies
> being able to inexpensively spawn a carefully tailored process regardless of the size and scope of the current process would be better.
It's called clone(2)
You're referring to something else, and maybe I'm using the term "zygote" incorrectly.
In all uses of zygotes that I have seen, here's what's really happening:
- `fork` is being used to reduce the cost of starting a process that has a high start-up cost. So, you start one process, run it through the expensive initialization, and then fork it from there to start new processes.
- To make this even faster, you have a pool of pre-forked processes sit around.
- Having pre-forked processes sitting around ready to be used is not expensive because of the CoW property and the fact that a process that forks and then immediately pauses will not have triggered any significant CoW yet.
So, the zygote optimization you speak of is in practice only meaningful on top of systems that are using an optimization uniquely enabled by `fork` (avoiding process initialization costs by cloning a process), and that zygote optimization is further optimized by another property of `fork` (memory sharing of forked processes that haven't done anything else yet).