Git is super mid. It’s a shame that Git and GitHub are so dominant that VCS tooling has stagnated. It could be so so so much better!
Are we back to "programming language X is slow" assertions? I thought those had died long ago.
Better algorithms win over 'better' programming languages every single time. Git is really simple and efficient. You could reimplement it in Python and I doubt it would see any significant slowness. Heck, git was originally implemented as a handful of low level binaries stitched together with shell scripts.
Python is absurdly slow - every method call is a string dict lookup (slots are way underused), everything is all dicts all the time, the bytecode doesn't specialize at all to observed types, it is a uniquely horrible slow language.
I love it, but python is almost uniquely a slow language.
Algorithms matter, but if you have good algorithms, or you're already linear time and just have a ton of data, rewriting something from a single-threaded Python program to a multithreaded rust program I've seen 500x speedups, where the algorithms were not improved at all.
It's the difference between a program running overnight vs. in 30 seconds. And if there are problems, the iteration speed from that is huge.
To be fair, Python as implement today is horribly slow. You could leave the language the same but apply all the tricks and heroic efforts they used to make JavaScript fast. The language would be the same, but the implementations would be faster.
Of course, in practice the available implementations are very much part of the language and its ecosystems; especially for a language like Python which is so defined by its dominant implementation of CPython.
Doesn't the Python VM have inline caches? [0]
Later on I also changed some of the algorithms to faster ones, but their impact was much lower than the language change.
Which is only to say: that rewrite away from python story can also work to show python doing its job. Risk reduction, scaffolding, MVP validation.
A bunch of low level binaries stitched together with shell scripts is a lot faster than python, so not really sure what the point of this comparison is.
Python is an extremely versatile language, but if what you're doing is computing hashes and diffs, and generally doing entirely CPU-bound work, then it's objectively the wrong tool, unless you can delegate that to a fast, native kernel, in which case you're not actually using Python anymore.
That's often true, but not "every single time".
One of the reason mercurial lost the dvcs battle is because of its performance - even the mercurial folks admitted that was at least in part because of python
No, it's always been true. It's just that at some point people got bored and tired of pointing it out.
Yes we are? The slow paths of mercurial have been rewritten in C (and more recently in Rust) and improved the perf story substantially, without taking away from the wild modularity and extensibility hg always had.
I doubt it wouldn't be significantly slower. I can't disprove it's possible to do this but it's totally possible for you to prove your claim, so I'd argue that the ball is in your court.
The reason that some more modern tools, like jj, really blow git out of the water in terms of performance is because they make good choices, such as doing a lot of transformations entirely in memory rather than via the filesystem. It's also because it's written in a language that can execute efficiently. Luckily, it's clear that modern tools like jj are heavily inspired by mercurial so we're not doomed to the ux and performance git binds us with.
Apparently I belong to the same club -- when I'm writing AWK scripts. (Arrays are hashmaps in a trenchcoat there.) Using hashmaps is not necessarily an indictment you apparently think it is, if the access pattern fits the problem and other constraints are not in play.
> It's amazing how much we've brainwashed folks to focus on algorithms and lose sight of how to actually properly optimize code. Being aware of how your code interacts with cache is incredibly important.
By the time you start worrying about cache locality you have left general algorithmic concerns far behind. Yes, it's important to recognize the problem, but for most programs, most of the time, that kind of problem simply doesn't appear.
It also doesn't pay to be dogmatic about rules, which is probably the core of your complaint, although unstated. You need to know them, and then you need to know when to break them.
It’s amusing you call Git fast. It’s notoriously problematic for large repos such that virtually every BigTech company has made a custom rewrite at some point or another!
For everything I've ever done, git was practically instant (except network IO of course). It's one of the fastest and most reliable tools I know. If it isn't fast for you, chances are you are on a slow Windows filesysrem additionally impeded by a Virus scanner.
IOW, what do you know that nobody else does?
You can visit any resource about git and branches will have a prominent role. Git is very good at branches. Mercurial fans will counter by explaining one of the several different branching options it has available and how it is better than the one git has. They may very well be right. It also doesn't matter, because the fact that there's a discussion about what branching method to use really just means Mercurial doesn't solve branches. For close to 20 years the Mercurial website contained a guide that explained only how to have "branches" by having multiple copies of the repository on your system. It looks like the website has now been updated: it doesn't have any explanation about branches at all that I can find. Instead it links to several different external resources that don't focus on branches either. One of them mentions "topic", introduced in 2015. Maybe that's the answer to Git's branching model. I don't care enough to look into it. By 2015 Git had long since won.
Mercurial is a cool toolbox of stuff. Some of them are almost certainly better than git. It's not a better product.
Git does not have such concept. That is a trade off and that trade off works great for projects managed like Linux kernel. But for smaller projects where there is a limited number of people working, the information preserved by mercurial could be very valuable.
It also had some really interesting ideas like change set evolution, which enabled history re-writing after a branch has been published. Don't know its current status and how well it turned out to be..
Maybe branching was an important reason to adopt git but now we'd probably be ok with a vcs that doesn't even support them.
Google and Meta don’t use Git and GitHub. Sapling and Phabricator much much better (when supported by a massive internal team)
I personally went from .latest.latest.latest.use.this (naming versions as latest) to tortoise SVN (which I struggled with) to Git (which I also was one of those "walk around with a few memorised commands" people that don't actually know how to use it) to reading the fine manual (well 2.5 chapters of it) to being an evangalist.
I've tried Mercurial, and, frankly, it was just as black magic as Git was to me.
That's network effects.
But my counter is - I've not found Mercurial to be any better, not at all.
I have made multiple attempts to use it, but it's just not doing what I want.
And that's why I'm asking, is it any better, or not.
That’s it. That’s why git won, you could put up open source libs with one for free and not the other.
Which is extra funny as the centralized service was the most important part of decentralized version control.
So git /did/ have something better than Mercurial after all, it was a 3rd party, but it still meant that it was massively better than Mercurial.
I've often thought this about github
Rebase does not make sense in Mercurial because it has the concept of fixed branches. A commit is permanently linked to the branch on which it was made. So you are supposed to use merges.
Same with force-pushing.
Believe me, I tried to have an open mind about it. Then one day I was getting ready to go on a work trip with a half-finished feature on my work laptop, and realised there was simply no in-model way for backing that wip up to the repo. If I lost my laptop, I lost the progress. mercurial-scm fails at SCM.
- rebasing in Mercurial simply means chopping a subtree off of the history and re-attaching it to a different parent commit. In that sense, rebasing is a very useful and common history-rewriting operation. In fact, it's even simpler and more powerful/versatile than in git, because mercurial couldn't care less if the sub-tree you are rebasing belongs to a branch or not: it's just a DAG. It gets transplanted from A to B. A may or may not be your checked commit, or be the tip of a branch, doesn't matter.
- that mercurial requires a configuration toggle before rebasing can be used (i.e. that the user need to enable the extension explicitly) is a way to encourage interested users to learn their tool, and grow its capabilities together with their knowledge. It's opinionated, it may be too much hand-holding for some, but there is an elegant simplicity in keeping the help pages and autocomplete commands just as complex as the user can take it.
