@lanodan@cks I think 9front probably tolerates a lot more risk (and has a lot less critical deployments) than OpenBSD. I also received the perception that OpenBSD really only care specifically about having no software required to work on the OS shipped from outside their base repository, and they have a pretty firm policy on what licences can be used in there; hence, their work in progress Game Of Trees git reimplementation.
@encthenet write(2) to a self pipe you already have open is also safe and well-trodden, in order to inject an event into your event loop. Some OSes also have event loop systems with a facility built for this, such as port_send(3C) from event ports on illumos.
@GeePawHill Definitely a big fan of small monoliths and SQLite and single VMs. Admittedly in AWS because it's been easy, but I am using almost no features of EC2 other than "a small VM please".