How hard is it to get a jobserver client right?

In November 2025, I’ve started working on steve, the jobserver for Gentoo. I wrote about it already, in the “One jobserver to rule them all” post. Back then, my main focus was on the motivation for a system-wide jobserver, and the technical details of getting it working. I have also mentioned a few client bugs we’ve discovered along the way.

Since then, we’ve found a few more bugs, as well as problematic design patterns. I think they’re kind of interesting, so I’ve decided to dedicate this post specifically to them. As a disclaimer, my aim is not to pick on specific projects; I’m bringing them up as real examples of what we’ve hit, and how that impacts jobserver operation.
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