Mononoke – A Mercurial source control server designed to support large monorepos

https://github.com/facebookexperimental/mononoke

by gfortaine • 8 years ago

106 31 8 years ago

github.com

kyrra3• 8 years ago

Btw, mercurial has a longer term goal to rewrite parts of hg in rust.

https://www.mercurial-scm.org/wiki/OxidationPlan

mikevm• 8 years ago

Why did Facebook choose Mercurial over Git?

michel-slm• 8 years ago

from a previous blog post:

"Our engineers were comfortable with Git and we preferred to stay with a familiar tool, so we took a long, hard look at improving it to work at scale. After much deliberation, we concluded that Git's internals would be difficult to work with for an ambitious scaling project."

https://code.facebook.com/posts/218678814984400/scaling-merc...

sanxiyn• 8 years ago

Note that Microsoft arrived at the opposite conclusion and wrote GVFS: https://github.com/Microsoft/GVFS

pjmlp2• 8 years ago

Probably because they prefer to use sane SCM systems.

hiccuphippo• 8 years ago

What is insane with the other ones?

jlebar• 8 years ago

There's some irony that this lives on...github.

/git evangelism strike force

gmueckl3• 8 years ago

They really should have put it on Bitbucket. Hosting code for a VCS publicly and using the most fiercely competing system for it just sends the wrong message. How did nobody catch this?

ethomson3• 8 years ago

I think that the message it sends is that we collaborate with each other - Mercurial and Git, Facebook's Mononoke and Microsoft's GVFS. And since GitHub is _the_ place where open source software development happens, that's where this is hosted.

We're not enemies. We're not competing. We're trying to make developers lives better, and there are a number of techniques that can work, and a number of tools that can help them.

ethomson3• 8 years ago

Git Community PM at Microsoft here: I'm very impressed by Facebook's source control team in general (and Mononoke in particular). They're doing a lot of interesting things, and they've developed a very opinionated workflow about working in their monorepo that is very helpful for their workflows.

Another comment suggests that there's "fierce competition" in the version control space. In fact, I think that there's fierce collaboration in the version control space! Durham Goode from their team gave an interesting talk at Git Merge 2017 about how they're using Hg and some of the interesting user-experience tools that they've built on top of it: https://m.youtube.com/watch?list=PL0lo9MOBetEGRAJzoTCdco_fOK...

I don't personally prefer Mercurial (I like Git, as you might have guessed), but I think that there's some opportunities to learn from their user experiences and perhaps add or improve some high-level Git commands.

rattray3• 8 years ago

While you're here, can you say anything about when beta users outside of MSFT/GH might be able to try GVFS?

Do you think GVFS will also be able to support "thousands of commits an hour"? (It prominently claims to support "millions of files").

stolee• 8 years ago

Your second question about "thousands of commits an hour" is actually a server scale question, as opposed to a GVFS question. The main difference is that GVFS is primarily client software plus some extra server protocols that a server must support.

I find the "thousands of commits an hour" measurement to be conflating multiple things. I'll split out my expectations in our experience with the Windows repo.

The Windows repository is hosted in VSTS and handles over 4,000 developers doing their daily work. This includes an average of 3,000+ pushes per day via the Git protocol. Each push may include multiple commits. At least 2,300+ pull requests are completed per day, which creates a new merge commit each time. Also, the build machines run daily and kick off a push as their first action to update a version number. This creates 250+ parallel pushes within a 10 second window, so a spike of concurrent pushes are supported by VSTS.

jsgf2• 8 years ago

Tech lead of Mononoke here. Thanks for your comments!

The experience of using Mercurial within FB is quite different from the stock open source one. We have many local extensions, as well as integrations with the rest of our developer infrastructure. We're definitely optimizing for the linear-history monorepo model.

We don't see things as a competition between hg and git, but between good developer experiences and bad. Thus far, we've found it easier to improve the developer experience with hg than with git, so that have been our main focus.

But we feel we're reaching the limits of what we can do with hg, which is why we're investing in Mononoke. We feel that version control in general has been pretty stagnant, and we're hoping to do some neat stuff over the next few years (based on Mononoke and other projects).

wodenokoto• 8 years ago

Most people might know the name from the 1997 anime [0], not really know what the word means, but recognize the "mono" part as "singular". But really, it means monster [1]

[0] https://en.wikipedia.org/wiki/Princess_Mononoke [1] http://jisho.org/word/%E7%89%A9%E3%81%AE%E6%80%AA

jsgf2• 8 years ago

Mono-repo -> we're focusing our efforts on few large repos

Mono-tone -> The first cryptographic Merkle-tree distributed source control system, which was a large influence on both Git and Mercurial.

Monotone was written by Graydon Hoare, who later went on to design Rust (I think he was actually designing proto-Rust at the time), so the reference to Monotone is to both Mononoke's function and implementation.

Mononoke – A Mercurial source control server designed to support large monorepos

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