Right, it's "I have to send 5 PRs to 5 different repos, get them all cross merged, and then at the end it's wrong anyways so I have to start all over".
Multirepo management is extremely frustrating compared to "it's all in the same folder".
Multirepo management is extremely frustrating compared to "it's all in the same folder".
Surely if it is an advantage to rename once in a ginormous, single code base there must also be leaky abstractions, poorly defined interfaces, god objects, etc present at the same time?
Whenever I find I need to rename anything across domains, it's a matter of updating the "core" repository and then just pulling the newest version.
Which means that you've got to do independent backwards-compatible changes anyway, and that for anything remotely complex, you are better off with separate branches (and PR/MRs) anyway.
Monorepos mostly have a benefit for trivial changes across all repos (eg. we've decided to rename our "Shop" to "Shoppe"), where it doesn't really take much to explain with multiple repos, but is mostly a lot of tedious work to get all the PRs up and such.
Sometimes you have to ship a feature. Shipping that requires changing 3 parts of your app. A lot of times that _entire_ set of changes is less than 100 lines of code.
Having a full vision of what is being accomplished across your system in one go is very helpful for reviewing code! It justifies the need for changes, makes it easier to propose alternatives, and makes the go/no-go operation much more straightforward.
At a smaller scale, you often see the idea of splitting frontend and backend into separate repos. Of course you can ship an API and then ship the changes to the frontend. But for a lot of trivial stuff, just having both lets you actually see API usage in practice.
I think this is much more applicable for companies under 100 people though. When you get super large you're going to put into place a superstructure that will cause these splits anyways.
Most projects start out as monoliths (which is good) and splitting up on this axis is unfortunately very hard/costly.
Unfortunately it's hard for me to recommend Bazel, it's such an uphill climb to get things working within that system.
ISTM that the complexity of managing any repo will be bounded by the size of that repo; a monorepo, being unbounded in size, will, in time, become arbitrarily complex to manage.
While a multirepo might occasionally require developers to apply changes to more than one repo at a time, I’ve never found this to be much more than a minor inconvenience; one that could be solved readily with simple tooling, if we had ever felt that the “problem” was even worth solving.
Multirepo also allows you to roll out that change incrementally instead of big banging all the time.
Meanwhile reviewers don't have context about changes, so it's easier to get lost in the weeds.
It's not always this, of course. But I think that way too many tools are based on "repo" being the largest element, so things like cross-repo review are just miserable.