Is Facebook still using mercurial? It seems that there was a blog post about it in 2014, but their repo[0] just seems to say that their codebase was originally based on/evolved from mercurial.
Mercurial is still actively developed, and isn't really "dead", although it did lose a lot of popularity and "mindshare".
Projects like Firefox and nginx use it, although others like Vim and Python switched to GitHub. I don't know if Facebook is still using Mercurial internally, but for their public stuff they use GitHub.
I think that if GitHub had supported Mercurial like BitBucket or Google Code it would still be a lot more popular, but ah well...
Has Facebook switched to Mercurial? In one news it says so, in the next one read it has a ~50GB Git repo. If they really switched, it would be a good advertisement for Mercurial and its capabilities.
You're right, I should have been more precise: They seem to be switching to Mercurial because they think it's easier to customize Mercurial in order to address scaling issues they're having. (And I'd guess that some of those customization are going to end up in a future Mercurial release.)
Btw, I'm pretty impressed by Facebook's open source efforts.
Mercurial is used at Facebook, but it is heavily customized and goes through Phabricator. Just like Google uses Piper, which is “like Perforce” and goes through Critique.
I didn't, the Hg dev simply used Facebook as a very large, well known software shop that uses Mercurial. We could swap out "Facebook" for "Mozilla" or "Nginx Inc." or a number of open source (either community or corporate backed) projects.
The definitely do. They migrated their repositories to mercurial a while ago. There are plenty of mentions of this fact on mercurial's development mailing list (mercurial-devel@selenic.com).
Facebook is a big user and backer of mercurial. I attended the last mercurial sprint in Facebook's London office (which was great, BTW). Facebook will also host the next mercurial sprint in New York. They have recently hired Matt Mackall, mercurial's creator. Several other mercurial core developers also work for Facebook and are paid to work on improving mercurial as their main job.
I believe at some point they considered both git and mercurial as their new VCS. They have some huge repositories (hundreds of thousands if not millions of commits) and a huge amount of people accessing those repositories. I think they found some scalability issues with git's performance with repos of that scale (http://comments.gmane.org/gmane.comp.version-control.git/189...). Apparently it was easier for them to improve mercurial's performance, perhaps because mercurial is written in python with some performance sensitive parts written in C. Over the last year they have made a lot of progress and mercurial's performance on huge repositories is now even better than it used to be.
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