I feel like we're well into the longtail now. Are there other SCM systems or is it the end of history for source control and git is the one and done solution?
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Mercurial still has some life to it (excluding Meta’s fork of it), jj is slowly gaining, fossil exists.
And afaik P4 still does good business, because DVCS in general and git in particular remain pretty poor at dealing with large binary assets so it’s really not great for e.g. large gamedev. Unity actually purchased PlasticSCM a few years back, and has it as part of their cloud offering.
Google uses its own VCS called Piper which they developed when they outgrew P4.
google also has a mercurial interface to piper
git by itself is often unsuitable for XL codebases. Facebook, Google, and many other companies / projects had to augment git to make it suitable or go with a custom solution.
AOSP with 50M LoC uses a manifest-based, depth=1 tool called repo to glue together a repository of repositories. If you’re thinking “why not just use git submodules?”, it’s because git submodules has a rough UX and would require so much wrangling that a custom tool is more favorable.
Meta uses a custom VCS. They recently released sapling: https://sapling-scm.com/docs/introduction/
In general, the philosophy of distributed VCS being better than centralized is actually quite questionable. I want to know what my coworkers are up to and what they’re working on to avoid merge conflicts. DVCS without constant out-of-VCS synchronization causes more merge hell. Git’s default packfile settings are nightmarish — most checkouts should be depth==1, and they should be dynamic only when that file is accessed locally. Deeper integrations of VCS with build systems and file systems can make things even better. I think there’s still tons of room for innovation in the VCS space. The domain naturally opposes change because people don’t want to break their core workflows.
It's interesting to point out that almost all of Microsoft's "augmentations" to git have been open source and many of them have made it into git upstream already and come "ready to configure" in git today ("conical" sparse checkouts, a lot of steady improvements to sparse checkouts, git commit-graph, subtle and not-so-subtle packfile improvements, reflog improvements, more). A lot of it is opt-in stuff because of backwards compatibility or extra overhead that small/medium-sized repos won't need, but so much of it is there to be used by anyone, not just the big corporations.
I think it is neat that at least one company with mega-repos is trying to lift all boats, not just their own.
Meta and Google both have been using mercurial and they have also been contributing back to upstream mercurial.
git submodules have a bad ux but it's certainly not worse than Android's custom tooling. I understand why they did it but in retrospect that seems like an obvious mistake to me.
Perforce is used in game dev, animation, etc. git is pretty poor at dealing with lots of really large assets
I've heard this about game dev before. My (probably only somewhat correct) understanding is it's more than just source code--are they checking in assets/textures etc? Is perforce more appropriate for this than, say, git lfs?
I'm not sure about the current state of affairs, but I've been told that git-lfs performance was still not on par with Perforce on those kinds of repos a few years ago. Microsoft was investing a lot of effort in making it work for their large repos though so maybe it's different now.
But yeah, it's basically all about having binaries in source control. It's not just game dev, either - hardware folk also like this for their artifacts.
Assets, textures, design documents, tools, binary dependencies, etc…
And yes, p4 just rolls with it, git lfs is a creacky hack.
And often binaries: .exe, .dll, even .pdb files.
Interesting. Seems antithetical to the 'git centered' view of being for source code only (mostly)
I think I read somewhere that game dev teams would also check in the actual compiler binary and things of that nature into version control.
Usually it's considered "bad practice" when you see, like, and entire sysroot of shared libs in a git repository.
I don't even have any feeling one way or another. Even today "vendoring" cpp libraries (typically as source) isn't exactly rare. I'm not even sure if this is always a "bad" thing in other languages. Everyone just seems to have decided that relying on a/the package manager and some sort of external store is the Right Way. In some sense, it's harder to make the case for that.
It's only considered a bad idea because git handles it poorly. You're already putting all your code in version control - why would you not include the compiler binaries and system libraries too? Now everybody that gets the code has the right compiler to build it with as well!
The better organised projects I've worked on have done this, and included all relevant SDKs too, so you can just install roughly the right version of Visual Studio and you're good to go. Doesn't matter if you're not on quite the right point revision or haven't got rough to doing the latest update (or had it forced upon you); the project will still build with the compiler and libraries you got from Perforce, same as for everybody else.
I would say it's considered a bad idea, since git comes from an OpenSource world and its implied understanding, where you don't depend on a specific binary release to reproduce your results, but your results can always be reproduced purely from source - binaries are just considered a product of "the plaintext truth recorded in your repository".
Sure, there are nuances to it as the need for ReproducibleBuilds [1] project demonstrated or people proving this concept of "bootstrapped reproducibility" to the extremes like Guix' full-source bootstrap [2], but I believe the fundamental understanding is the same.
[1] https://reproducible-builds.org/
[2] https://guix.gnu.org/en/blog/2023/the-full-source-bootstrap-...
> It's only considered a bad idea because git handles it poorly. You're already putting all your code in version control - why would you not include the compiler binaries and system libraries too? Now everybody that gets the code has the right compiler to build it with as well!
No arguments here, it makes perfect sense to me as a practice. It's shortsighted to consider only "libraries" (as source, typically) to be "dependencies"--implicitly you're relying on a compatible compiler version/runtime/interpreter (and whatever those depend on) and etc
What was the nature of this project? Was this something related to game development?
That seems to be the only domain where this approach is used (from what I've heard).
Yes, this was a video game, targeting games consoles - so the executable statically links with pretty much everything, including stuff that would count as part of the OS on a PC. And then, if you can make sure everybody builds with the same libraries then you can be sure that everybody is running the same code. (I imagine this approach is also used for embedded development sometimes, another case where the build artefacts cover a much larger percentage of what gets run on the target than is the case with a PC.)
I will admit that even though I think it might be worth doing (and not doing it because your version control system doesn't make it easy is the worst reason for not doing it!), I'm not sure I'd consider it absolutely mandatory, certainly not for video games anyway. Most projects I've worked on haven't done this, and it's been fine, especially if you have a CI system doing the builds - and now the individual developers' systems just have to be roughly right. But it is nice to have, if you've got the right combination of personpower and institutional will to actually do it. It eliminates a whole category of possible issues straight away.
(I'd like to think that for safety critical stuff like medical or automotive this sort of approach, but done even more carefully, would be par for the course...!)
why is this still the case ?
I've been checking in large (10s to 100s MBs) tarballs into one git repo that I use for managing a website archive for a few years, and it can be made to work but it's very painful.
I think there are three main issues:
1. Since it's a distributed VCS, everyone must have a whole copy of the entire repo. But that means anyone cloning the repo or pulling significant commits is going to end up downloading vast amounts of binaries. If you can directly copy the .git dir to the other machine first instead of using git's normal cloning mechanism then it's not as bad, but you're still fundamentally copying everything:
$ du -sh .git
55G .git
3. The cure for this (git lfs) is worse than the disease. LFS is so bad/strange that I stopped using it and went back to putting the tarballs in git.
This is a problem that occurs across game development to ML datasets.
We built oxen to solve this problem https://github.com/Oxen-AI/Oxen (I work at Oxen.ai)
Source control for large data. Currently our biggest repository is 17 TB. would love for you to try it out. It's open source, so you can self host as well.
Why would someone check binaries in a repo? The only time I came across checked binaries in a repo was because that particular dev could not be bothered to learn nuget / MAVEN. (the dev that approved that PR did not understand that either)
Because it’s way easier if you don’t require every level designer to spend 5 hours recompiling everything before they can get to work in the morning, because it’s way easier to just checkin that weird DLL than provide weird instructions to retrieve it, because onboarding is much simpler if all the tools are in the project, …
And it’s no sweat off p4’s back.
Hmm, I do not get it.... "The binaries are checked in the repo so that that the designer would not spend 5 hours recompiling" vs "the binaries come from a nuget site so that the designed would not spend 5 hours recompiling".
In both cases the designer does not recompile, but in the second case there are no checked in binaries in the repo... I still think nuget / MAVEN would be more appropriate for this task...
Everything is in P4: you checkout the project to work on it, you have everything. You update, you have everything up to date. All the tools are there, so any part of the pipeline can rely on anything that's checked in. You need an older version, you just check that out and off you go. And you have a single repository to maintain.
VCS + Nuget: half the things are in the VCS, you checkout the project and then you have to hunt down a bunch of packages from a separate thing (or five), when you update the repo you have to update the things, hopefully you don't forget any of the ones you use, scripts run on a prayer that you have fetched the right things or they crash, version sync is a crapshoot, hope you're not working on multiple projects at the same time needing different versions of a utility either. Now you need 15 layers of syncing and version management on top of each project to replicate half of what just checking everything into P4 gives you for free.
Because it's (part of) a website that hosts the tarballs, and we want to keep the whole site under version control. Not saying it's a good reason, but it is a reason.
There are some other solutions (like jujutsu, which while using git as storage medium, has some differences in the handling of commits). But I do believe we reached a critical point where git is the one stop shop for all the source control needs despite it's flaws/complexity.