The creator of Jujutsu has joined ERSC • Hacker News Board

Re: The creator of Jujutsu has joined ERSC

#81

Post by yegle » Tue, Sep 01, 2026, 7:36 PM UTC

drsouth wrote: post #73

yegle wrote: post #67

Earlier quoted context omitted.

Mercurial is too slow. Even with chg common commands like `hg status` may take hundreds of milliseconds. JJ is fast. Internally `jj log` taking more than 500ms is tracked as bugs.

[dead]

Well I did not answer your second part of the question, only the first part of comparing Mercurial vs Git.

Now to the second part: I think speed still plays a role back when Bitbucket and Google Code provides Mercurial hosting and people were comparing Mercurial with Git. Eventually GitHub won the competition, so then we kinda stuck with Git.

Re: The creator of Jujutsu has joined ERSC

#82

Post by vaylian » Tue, Sep 01, 2026, 7:36 PM UTC

drsouth wrote: post #66

yegle wrote: post #63

Earlier quoted context omitted.

A term coined within Google that describes the best part (to me at least) of jj: delayed conflict resolution. You worked on multiple things, you sync with the upstream, then boom now you have conflicts in one or more of your local branches. Instead of immediately presenting you a conflict resolution view (usually 3 pane vimdiff) and you'll have to resolve at the sync time, the commits are simply marked as "have confl…

> And for a chain of commits that all have conflicts, chances are fixing the first conflict automatically resolves all other conflicts in the chain, thanks to the auto-rebasing feature. What happens if one is unlucky and the conflicts are not automatically resolved from changes to the first commit? Does that potentially imply more work overall than if one was using a VCS that forced conflict resolution earlier, like…

git doesn't force conflict resolution earlier. It forces conflict resolution the moment you pull changes from upstream. jj allows you to go back to the first conflicting commit and then fix things there. That first conflicting commit is most likely a lot more similar to the upstream code than your newest commit and therefore it is easier to fix.

Re: The creator of Jujutsu has joined ERSC

#83

Post by underdeserver » Tue, Sep 01, 2026, 7:36 PM UTC

drsouth wrote: post #62

tcoff91 wrote: post #55

Earlier quoted context omitted.

I absolutely love jj (just check my HN comment history). One thing I'd love to see in jj though that git does better is copy tracking. If somebody renames a file upstream, and you go to rebase your commit that touches that file onto main, jj doesn't handle this very well compared to git. Do you have any idea if this is coming to jj soon?

Do you happen to have or know of any good open source projects on any public platform like GitHub, gitlab or Codeberg, that uses Jujutsu/jj?

If I remember correctly, Mitchell Hashimoto uses it for Ghostty (probably under the git backend).

Re: The creator of Jujutsu has joined ERSC

#84

Post by saghm » Tue, Sep 01, 2026, 7:37 PM UTC

drsouth wrote: post #57

steveklabnik wrote: post #4

Working with Martin has been a real pleasure, and we'll have some more stuff to talk about very soon!

Will this have any chance if Jujutsu/jj doesn't get more traction? The effort to learn a new VCS is less than for a programming language, but many developers have not learned git in depth, and Mercurial and others have not gained a lot of traction.

I'd argue that the reason a lot of developers have not learned git in depth is because it's actually kind of terrible from a UX standpoint (lots of inconsistent naming of things and somewhat leaky abstractions), and that Mercurial faced an uphill battle in large part because it lacked compatibility with what people were already using. I haven't used Mercurial, but from what I've heard quite a lot of how jj does things is similar to Mercurial, just in a way that's compatible with git. I haven't used git directly for over a year in favor of using jj despite exclusively using git repositories, and no one I've worked with has even needed to be aware.

Re: The creator of Jujutsu has joined ERSC

#85

Post by underdeserver » Tue, Sep 01, 2026, 7:37 PM UTC

steveklabnik wrote: post #13

opem wrote: post #11

Earlier quoted context omitted.

excited for what you guys would be coming up with ;) btw, did Martin leave google?

Thanks! Martin left Google for this, yes.

Wasn't it partially owned by Google? Or are they just a contributer now?

Re: The creator of Jujutsu has joined ERSC

#86

Post by tonfa » Tue, Sep 01, 2026, 7:37 PM UTC

drsouth wrote: post #65

jph wrote: post #17

Jujutsu is a better smarter git. It's a great convergence of better UX, plus more expressive, plus easier to use. If you haven't tried jj yet, take it for a spin and see how you like it.

How does it compare to Mercurial? And why would it get more traction than Mercurial?

> And why would it get more traction than Mercurial?

There's no network effect headwinds, it's interoperable with git (I assume most people using jj have an upstream repo that's on git).

Re: The creator of Jujutsu has joined ERSC

#87

Post by Kinrany » Tue, Sep 01, 2026, 7:38 PM UTC

drsouth wrote: post #57

steveklabnik wrote: post #4

Working with Martin has been a real pleasure, and we'll have some more stuff to talk about very soon!

Will this have any chance if Jujutsu/jj doesn't get more traction? The effort to learn a new VCS is less than for a programming language, but many developers have not learned git in depth, and Mercurial and others have not gained a lot of traction.

It doesn't require that everyone switch at the same time, unlike other VCSs.

Re: The creator of Jujutsu has joined ERSC

#88

Post by saghm » Tue, Sep 01, 2026, 7:38 PM UTC

drsouth wrote: post #65

jph wrote: post #17

Jujutsu is a better smarter git. It's a great convergence of better UX, plus more expressive, plus easier to use. If you haven't tried jj yet, take it for a spin and see how you like it.

How does it compare to Mercurial? And why would it get more traction than Mercurial?

My relatively ignorant take is that it's pretty similar to Mercurial, except that it's compatible with git repos, which is also the answer to why it might get more traction. At least from my standpoint, it also doesn't need to get traction, because I freely use it with git repos without any of my coworkers needing to use it as well (although they might! I have no idea, just like they probably don't know I use it)

Re: The creator of Jujutsu has joined ERSC

#89

Post by yegle » Tue, Sep 01, 2026, 7:40 PM UTC

ksymph wrote: post #26

So if I understand correctly: ERSC is working on an alternative backend for jj other than git (and presumably providing related infrastructure)?

I think it's closer to: develop something similar to Google's Piper as (hopefully!) an open source project and sell this to enterprise, similar to Perforce's business model but with the benefit of an excellent and well received frontend tool.

Re: The creator of Jujutsu has joined ERSC

#90

Post by saghm » Tue, Sep 01, 2026, 7:42 PM UTC

steveklabnik wrote: post #19

fallat wrote: post #12

Someone will have to explain the value proposition to me... We have git. jujutsu works with git. git can do everything jujutsu can do (otherwise, jujutsu couldn't work with git). Thus, jujutsu is a UX / new steering wheel. ERSC is trying to be a GitHub competitor with what surplus value? Don't get me wrong, GitHub has a slew of its own problems, but I have not seen any commentary on how ERSC addresses any of the down…

We'll be saying more about this very soon, but the short version is this: we are not building a GitHub competitor in the way that SourceHut or Codeberg are. We are building infrastructure for enterprises, not a social coding site. While jj works with git, it doesn't have to. jj has the ability to work with many backends. Git is the popular one in the open source world, but that doesn't mean that other ones are not po…

All but one of my employers have used either Github or Gitlab, and at every one of them there were a litany of complaints about whichever one we were using. It's kind of surprising to me that someone might not immediately recognize that there's certainly potential there for something better suited to what companies are actually looking for. Obviously there's no guarantee of success, and maybe the problem is too hard to solve, but that's pretty much how any company starts out!