I have an Arch Linux server that was working fine, but was pretty far out of date. After getting everything settled with pacman -Syu the web service it runs would no longer load, just a generic 503 error. I can't seem to get any detail about the error other than from the Apache logs:
Failed to connect to mod-mono-server after several attempts to spawn the process.
In addition to this, I'm using the "event" MPM model. Yet, for some reason Apache will initially startup around 8 processes, and then with each request to the website, seems to startup 8 more without killing any of the previous processes. It will basically continue to spawn processes until it hits the process resource limit, or until it's out of RAM, whichever comes first. Each process will consume all of the CPU it can.
mod-mono-server itself will start, though it does take a few seconds, and a static (not using mono) site on the same apache instance works fine. None of the journald logs, nor other logs I can find in /var/logs gives any kind of info
How do I begin to even get more info about this error? And of course, how can I fix it?
Some compatibility problem with mod_mono and new versions of systemd appear to be the culprit, with no dev response or acknowledgement from the mod_mono team: https://bbs.archlinux.org/viewtopic.php?id=243508