Another daemon for managing control groups [LWN.net]

Another daemon for managing control groups

Posted Jan 4, 2014 14:50 UTC (Sat) by anselm (subscriber, #2796)
In reply to: Another daemon for managing control groups by cas
Parent article: Another daemon for managing control groups

the truth is that systemd just isn't good enough to be worth the price of loss of modularity and replacability (nothing could be good enough to be worth that price)

Any »modularity« in System-V init is there purely by accident. Actual »modularity« would imply a certain amount of unity of design and basic concepts, and communication between the components by means of well-defined and documented interfaces. None of these apply to System-V init and its associated tools such as inetd, cron, etc.

It's not as if System-V init had been consciously designed the way it is. It is a hodgepodge of stuff from different sources that were developed separately from each other, don't interact well (if at all) and are each configured completely differently from the rest. If there is a long-overdue opportunity to replace this utter mess by something that has actually been properly thought out as a complete system, works a lot better in real life, and is easier to understand, develop for, maintain, teach, and learn, then I'm all for it.

Another daemon for managing control groups

Posted Jan 25, 2014 20:50 UTC (Sat) by Baylink (guest, #755) [Link] (4 responses)

No, the modularity comes from *the pieces not all being one big piece with no visibility or lines of separation*.

Yes, the design of sysVinit is a *bit* rough. But it works, and it's easy to understand if you know basic Unix, and you don't have to read thousands of lines of source to figure out what it's doing.

And if one part of it falls over, ps will tell you, and you can kill just that one part.

And you can grep the damn logs.

Another daemon for managing control groups

Posted Jan 26, 2014 1:20 UTC (Sun) by HelloWorld (guest, #56129) [Link]

> Yes, the design of sysVinit is a *bit* rough. But it works,
It *doesn't work*. Stop denying it, sysvinit can't even stop a service reliably and correctly.

> and you don't have to read thousands of lines of source to figure out what it's doing.
Yeah, you just have to read thousands of lines of shell. With systemd otoh, you read *documentation*. You know, this stuff that is actually meant to be read by humans. Because unlike the sysvinit quagmire, systemd actually *has* documentation that's worth mentioning.

> And if one part of it falls over, ps will tell you, and you can kill just that one part.
Yeah, like systemd somehow magicall broke ps.

> And you can grep the damn logs.
You can do that with journalctl too. But actually most people don't do it, because it *sucks* and just using the domain-specific features of journalctl is easier, faster and more robust.

Another daemon for managing control groups

Posted Jan 27, 2014 19:38 UTC (Mon) by anselm (subscriber, #2796) [Link] (2 responses)

The current init/service activation infrastructure (System V init, inetd, cron, …) does not have anything worth calling »a design«. It is cobbled together out of random pieces from different sources and the amazing thing is that it works at all. The pieces don't talk to one another and are all configured differently. If it had in fact been »designed« you would expect at least a minimum of consistency and cooperation between the pieces.

If somebody proposed this setup today as a new system they would be laughed out of the lecture theatre. The only reason this is still in actual use at all is that for the longest time nobody has dared come up with an alternative. Most of the other Unix-like systems have replaced it long ago.

People always cite »the Unix philosophy« as »do one thing and do it well«, and point to System V init as a prime example of this approach. This disregards the obvious fact that while SysV init is surely doing something, there is no way that one could claim it is doing it well.

Another daemon for managing control groups

Posted Jan 27, 2014 20:45 UTC (Mon) by khim (subscriber, #9252) [Link] (1 responses)

This disregards the obvious fact that while SysV init is surely doing something, there is no way that one could claim it is doing it well.

It does pretty decent work on scaring newbies away from Linux. Perhaps that is the thing is was designed for? Of course it's kinda overenginered for such a use case, you can create a much smaller and simpler mess which will be much scarier.

Another daemon for managing control groups

Posted Jan 27, 2014 22:40 UTC (Mon) by nix (subscriber, #2304) [Link]

Someone needs to implement an init system as an IOCCC entry, clearly.