A Git helper tool that breaks large merges into parallelizable tasks

Posted by schusterfredl 4 days ago

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Comments

Comment by redoh 4 hours ago

We had a massive merge at work last year where two teams diverged for months on a shared codebase. It took three people a full week to resolve everything, and the worst part was stepping on each other's conflict resolutions. Splitting the merge into independent slices that people can work on in parallel would have saved us a lot of pain. The integration branch approach where non-conflicting changes land automatically is a nice touch too.

Comment by rwmj 4 hours ago

> where two teams diverged for months on a shared codebase

There's your problem. What was the reason for not merging small changes, bug fixes, refactors and such, early?

Comment by wren6991 3 hours ago

Brought to you by classics like "how do I join all of these pthreads that I've detached?"

Comment by _s_a_m_ 1 hour ago

Yeah, that is a terrible idea. Before you do this, you'll first do a redesign and split things up in packages that can be separately updated and installed.

Comment by locknitpicker 3 hours ago

> We had a massive merge at work last year where two teams diverged for months on a shared codebase.

There is no tool in the world that can save you guys from yourselves. There is a reason why Agile methodologies put such a premium on continuous integration.

Comment by throwaway613746 1 hour ago

[dead]

Comment by schusterfredl 4 days ago

mergetopus is a tool that helps teams follow a structured workflow for very large merges by splitting one risky merge into parallelizable tasks:

* one integration branch for trivial/non-conflicting merge results * optional slice branches for selected conflicted files * original annotate/blame information is retained

Comment by iamjs 9 hours ago

I have long wanted a tool to help split large diffs into smaller semantic changes. When you're working on a feature, for example, and end up refactoring along the way, you may wish to have your refactor reviewed and merged without any new functionality.

Comment by Cthulhu_ 4 hours ago

That's when you should stop your work, make a new branch from main, do the refactoring and offer it separately; it's about (self) discipline in the end. You can probably also do something creative with cherry-pick and the like.

Comment by hebetude 2 hours ago

It’s painful but this is the way. Especially if your team is slow at merging.

Comment by locknitpicker 9 hours ago

> * one integration branch for trivial/non-conflicting merge results

Doesn't this mean the integration branch will be missing key updates, thus it's expected to be broken?

Comment by schusterfredl 6 hours ago

hey, someone actually reads the docs :D

no, the integration branch is not "broken", its just not complete until all slices have been merged INTO the integration branch - after all slices have been merged, the integration branch is complete, yet has a non-optimal history (and most likely a wrong blame because of how git resolves the blame), - therefore the "kokomeco" branch is created after the slices have been merged, - there the original intended merge is done because the outcome of the conflicts is already known from the integration + slice branch merges.

Feel free to open issues/questions in the repo if you're interested, I merely stumble by ycombinator

Comment by locknitpicker 3 hours ago

> no, the integration branch is not "broken", its just not complete until all slices have been merged INTO the integration branch

What do you call an incomplete branch that is missing slices?

> after all slices have been merged, the integration branch is complete, yet has a non-optimal history (and most likely a wrong blame because of how git resolves the blame)

What is the value proposition then? Broken integration branches that leave a suboptimal history? What am I missing?

> Feel free to open issues/questions in the repo if you're interested, I merely stumble by ycombinator

I don't think there is a compelling reason to use this tool. It messes commit history and leaves integration branches in a broken state? Not a great selling point. The alternative would be to sync with branches using standard flows such as rebasing and merges from base branches. You don't need a tool for that, only a hello world tutorial on Git.

Comment by swiftcoder 1 hour ago

> What do you call an incomplete branch that is missing slices?

"incomplete", evidently. I don't see a real alternative here - you need some working space for an in-progress merge, and if you want to do the merge collaboratively, you'll want it on a branch. Just don't run CI on that branch till the merge is complete.

> Broken integration branches that leave a suboptimal history? What am I missing?

You appear to be missing the next step, where they use the merge resolutions from that suboptimal history to replay the original merge, giving you back nice clear history (and at this point, the integration branch can be discarded, presumably)

Comment by spectrumx 4 hours ago

It's a good tool to solve a problem that, in truth, shouldn't be present at all in well-behaved engineering teams.