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I'm pretty ignorant on Unikernels so maybe there's another solution, but not being able to `fork()` is a significant problem for many applications.

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On Unix you typically fork as a part of initializing your application in order to demonize. Or when you are executing another program so a fork/exec.

The first one isn't needed in a unikernel. You are already demonized when you boot up.

The second use is not available to unikernel applications. The limitation of a single application per vm applies.

My understanding is that unikernels are single-application by design. I agree that a mechanism to spawn other apps is useful, but in this case it won't be a simple fork but the creation of a complete new os instance.

I suspect GP is referring to single applications that aren't single process. Postgres is one example. Vacuum and checkpoint are separate processes.

Applications also sometimes have separate processes for sentinal functions, logging, etc. Or default configurations that are multi process, like many load balancers, web servers, API gateways, etc.

There are plenty of applications that used multiple processes.

Absolutely. And most of those are deemed out of scope for Unikernels.

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