3 ms·

I have also had a little mismatch with upstart for a particular application - the app itself spawns new processes in response to user input, but upstart can on

I have also had a little mismatch with upstart for a particular application - the app itself spawns new processes in response to user input, but upstart can only track the main app not the children. I am curious - precisely knowing when an app is running and when its not seems inherently dependent on the app and your definition of "running" for that app. Tracking apps from the system level in terms of processes etc. can only go so far. How do the init systems you mentioned tackle this?

Shish2k 11y ago
> precisely knowing when an app is running and when its not seems inherently dependent on the app [...] How do the init systems you mentioned tackle this? In systemd's case, it provides an API so that the app can explicitly say "I am now ready to receive requests", among other things. http://www.freedesktop.org/software/systemd/man/sd_notify.html http://www.freedesktop.org/software/systemd/man/sd_notify.ht... (I've also found the related watchdog functionality very useful -- once you tell the init system that your daemon is ready to serve requests, then you can also tell it every time a request is completed; then if you go for say 10 seconds without serving a request, init will assume that your service has hung and kill/restart it. I've seen a small number of daemons do this for themselves, but that number is nowhere near 100%, and even those who do implement it don't do it as well as systemd does.)