[humanrebar]

I suspect for that number of projects monorepos make a lot of sense.

The major technology organizations we hear about usually have at least several monorepos, due to the legacies of acquisitions and mergers if nothing else.

At the scale of thousands of subprojects, I am not entirely sure the benefits are as advertised. There will be support of subprojects forked to public github.com or gitlab.com if nothing else. And there will be external dependencies to manage; system level libraries like openssl and libc if nothing else. Even if they are vendored in to the monorepo, any upstream regression is a significant problem in a monorepo... and the problem sometimes has to be solved in a big bang instead of incrementally.

[shados]

Going from 15 to 3 is definitely a different discussion from going from 7000 to < 5.

At 15, it feels like it's kind of just a toss up. We have several thousand repos, and sometimes we see 5-10 of them that really should be grouped, and we do so. Sometimes we see 1 repo that has 5-10 projects in it, and we break them down. Whatever works.

But when the entire org is on a dozen project you're potentially in the worse of both worlds. Your repos aren't small enough or aligned with team ownership enough to really benefit from it. So its straight overheard.

[umanwizard]

FWIW at least 95% (anecdotally) of Facebook’s main code is in two gigantic monorepos: fbsource and www. (The other major repos are for configuration-related stuff).

Last I heard there were plans to move www into fbsource.

There are certainly not random dependencies on public GitHub pages. Everything is versioned.

There is a mind boggling amount of custom tooling to make this work.

[humanrebar]

The versioned external dependencies work for systems that support semantic versioning. Some dynamic languages. Some C. Definitely nothing with a non-C ABI.

But "not working" looks like fixing an unknown number of bugs across the various subrepos. Because permanently forking upstream it never applying security patches isn't a good business model.