Honestly you're probably right. But I'm too much of a nigger to actually learn s6. At least I haven't put in the time after reading about it.
But it sounded like it's probably about as fast as it gets. Since it's running its stuff as compiled binaries if I remember correctly.
Ultimately, all the hard stuff is around process and PID monitoring, restarting things as necessary if they crash. S6 is more of a supervisor, supervisors can function perfectly well as an init system. The important part about s6 is that it does not have to be PID 1. That means you can start it and use it for arbitrary processes, not just for system startup.
I even have s6 running under openrc in Gentoo for my user mode daemon (hello dbus, pipewire). But why the autism instead of just dumping everything in a script and running that instead? Because the supervisor automatically restarts anything that crashes, I let it do what it does best, automatically restarting my stuff for me instead of writing yet another solution for process monitoring.
I think some Skarnet stuff like execline seems a bit of a solution in search of a problem, but big S has his own priorities, and I expect I'm too much of a mere mortal to properly understand. Plenty of inits are minimal C wrappers around a shell script.
You can write shell scripts as run files for s6, so long as you remember to chmod +x it. It can even be perl or python or binary programs written in C, s6 doesn't care. I used a simple shell script to load some settings file to pipewire under s6. Execline is for in case you ABSOLUTELY DO NOT WANT TO FORK without relying on external executables or shell expansion uncertainties, but I have no problems with that.
The only part I don't like is needing to compile your service directories or having live directories, but I guess that's one way it monitors processes.
In many cases it is legitimately faster to identify the problem and make the fix locally than to go shopping around for alternatives, especially when the thing you're using 99% does what you want. Doing this regularly will make you a well-read programmer, skilled at debugging, comprehending, and modifying code you only found out about today.
I used gentoo enough that I have plenty of /etc/portage/patches customization. It's great I don't need to bug anyone if I want to change something for my own use, nor do I need any permission. Many of them are one-liners too. It gets auto applied when packages are updated as well, but if it doesn't, time to update the patch.
