[WesolyKubeczek]

Well, do systems like, say, FreeBSD even support facilities functionally equivalent to control groups? Even if they do (which they don’t), it would be a whole new separate implementation, and there’s not enough interest from anyone who can do it to roll their sleeves and work on it.

[stonogo]

FreeBSD, specifically, has had jails and Capsicum longer than systemd has existed, and rctl (aka Resource Limits) for about a decade now.

Like I said, systemd is a great init system but it really did not bring anything to the table as far as service management. Apple's abdication of the problem makes sense since they're tightly focused on workstation ever since killing the Xserve line in 2011.

[WesolyKubeczek]

Can rctl give me an ability to run two instances of the same executable with different limits?

[zare_st]

Yes

[zare_st]

Answer to question - yes, and more. Jails+rctl (available since 2012) is not cgroups it's cgroups+SELinux+APParmor. Vanilla linux container is not a security barrier, vanilla FreeBSD jail is.

In practice this means more seamless 'isolation' in Linux case but that isolation is weak. Which perfectly corresponds to FreeBSD looking at server uses 99% of the time and Linux looking at the desktop too.

About your conclusion, I don't think that's based on anything so please do write on what facts do you base the assessment that FreeBSD has no resource limiting and isolation features, and that it would be a 'separate implementation', as FreeBSD always tends to upgrade and not change tools and interfaces, and that there is not enough interest from anyone to implement it, as most major FreeBSD features are actually paid for by FreeBSD sponsors.

[WesolyKubeczek]

I don’t assess FreeBSD doesn’t have resource limits. I’m stating the fact that prior to systemd, issuing a service restart command under any Unix at all was prone to inheriting any rlimits your shell session happened to have, which could in turn lead to unforeseen consequences like sudden memory/file handles failures or sluggish I/O, depending on how shell sessions are being set up.

Implementing a service manager that can understand and interpret systemd unit files for FreeBSD would require it to be based on completely different kernel mechanisms than Linux, feature parity aside. I can easily see that people with enough skill won’t see the need to be bothered to write such a piece of software, and those who don’t will just shrug and stay on Linux.

[zare_st]

Why would systemd unit files matter for FreeBSD? FreeBSD has its own rc system and its own ports and packages and maintainers. If and when some major software starts lagging behind the upstream because of runtime issues, then it's time to discuss the alternatives. Right now such things do not happen.

FreeBSD had to mock several parts of systemd in order to port newer GNOMEs that are dependent on systemd. rc still runs this software, but unfortunately software depends on systemd sockets which is absurd design choice but here we are. Again mocking the absurd interprocess part is the way to go, as opposed to supporting entire specification and API of systemd.

"Any unix" doesn't cut it, too general, too broad. You did ask in dual sense in your original question but then you specifically stated FreeBSD as an example; so I'm answering for FreeBSD specifically.

The problem that I have with opinion in your post is an implication about groups of people - people with skills that should supposedly write a systemd clone for FreeBSD or other Unices, and people without skills that are supposedly waiting for the first group to do some work so they can enjoy systemd on *BSD or wherever. Let me be blunt here, I can assure you this is not the case. Systemd is not a factor for anyone in BSD world and it's a factor only for people that would like to migrate from Linux and retain their usual workflow and muscle memory.

[simoncion]

> I’m stating the fact that prior to systemd, issuing a service restart command under any Unix at all was prone to inheriting any rlimits your shell session happened to have...

IFF the service manager you used was either incompetently written, or had this behavior as an intentional feature. This is a problem (like many other problems that the Systemd Cabal addressed) that was known and resolved by many other folks substantially before systemd came along.

Like, think about it for a second. You're saying that systemd has a mechanism to avoid this problem. Systemd uses tools that have been available in Linux for a long time. (I think the newest tool it uses is control groups, which are like seventeen years old.) Are you really saying that none of the big players in the space (nor any of the sysadmins that got REALLY pissed off at the bullshit unreliable behavior that you describe) ever hit upon the technique that systemd uses to avoid this problem?

As I (and many other) keep saying, systemd did solve many problems... but it was also not the first to solve many of those problems.

> Implementing a service manager that can understand and interpret systemd unit files for FreeBSD...

Unit files kinda suck, and so much of the behavior of the various options inside of them are underspecified. (How do I know? I've gotten badly burned in production repeatedly by underspecified behavior shifting out from under me as the software implementation changed.)

There's no good reason to use Unit files outside of systemd... especially when services with non-trivial startup and/or shutdown procedures have to have systemd run helper programs because it's just impossible for systemd to handle every conceivable startup and/or shutdown requirement without embedding a general-purpose scripting language inside of systemd (which would just be fucking stupid).