I see that you've rewritten your AI generated reply there. So when have you used mlock in production for Go services, the way you're advising others to do? What were the circumstances?

I did not rewrite anything.

Yes, I was and still running go and zig binaries with mlockall. Apps have large in-application caches and also perform large streaming reads of datasets bigger than available RAM. If it happens that several streaming reads running at same time, they push memory pressure hard enough, so kernel swaps out cold parts of in-app caches. That later leads to elevated latencies => mlockall to avoid that.