Re: Please stop hating on sysvinit (was Re: do packages depend on lexical order or {daily,weekly,monthly} cron jobs?)

[Vincent Bernat <bernat@debian.org>]

 ❦  8 août 2019 21:47 +02, Simon Richter <sjr@debian.org>:

>> inetd performance is very low because it needs to spawn one instance for
>> each connection. systemd socket activation has absolutely 0 overhead
>> except on the first connection (where systemd needs to start the
>> service).
>
> If you specify "wait" instead of "nowait" for a TCP service, your service
> is handed the listening socket, and can continue to accept more connections
> on that socket.
[...]

My bad, I didn't know that.

> This feature went unused not because noone thought of it, but because there
> is no real world use case that benefits from it. Either the service is used
> regularly, then it makes sense to keep the daemon in memory, or it isn't,
> then the reduced complexity for one-shot services (to the point where you
> can use a shell script as a service) is the benefit.

Reality seems different. Almost nothing was using inetd (tftpd is the
only daemon I have in mind), while many daemons adopted systemd socket
activation. For example, OpenSSH (optional), Docker (by default), CUPS
(by default), libvirt (by default, several services), Dovecot (by
default). It seems the key difference is that socket-activated services
are regular services. They can be started manually if we want them to be
and they inherit everything systemd is able to provide to services.
-- 
Localise input and output in subroutines.
            - The Elements of Programming Style (Kernighan & Plauger)

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