CI is very slow

Stream: Brownian motion

[Rémy Degenne]

The documentation step of our CI now takes hours. I think it's doing that since I bumped to 4.22.0-rc2 . The last successful CI on a merge to master took almost 6 hours. Anyone feels like investigating?
I'll tag @Pietro Monticone since he's a CI expert.

[Pietro Monticone]

It's all due to docs generation: a combination of having import Mathlib and the issues discussed in #general > Why is doc-gen4 so slow?

There is another docs cache issue (which is not causing the inefficiency, but it's related) in the new docgen-action which will be solved in the next few days.

CC: @Anne Baanen

[Rémy Degenne]

I don't have import Mathlib anymore, and until that recent dependency bump it was taking a bit more than 30 minutes (or 80 minutes when I still had an import Mathlib). The fact that it takes 6 hours to build the docs is new.

[Rémy Degenne]

The current run: https://github.com/RemyDegenne/brownian-motion/actions/runs/16023065753/job/45204400417 (already 3 hours long)

[Pietro Monticone]

Oh, I see. It seems to be due to the latest release then...

In the meantime, I would recommend disabling doc generation by setting api_docs: false in your workflow:

      - name: Compile blueprint and documentation
        uses: leanprover-community/docgen-action@f78d5a9a1a728288aef64bde6f133d30a8511cb7 # 2025-06-27
        with:
          blueprint: true
          homepage: home_page
+         api_docs: false

This should serve as a temporary workaround until the docgen-action cache issue is resolved which would reduce the workflow compilation time.

[Rémy Degenne]

Thanks, I'll do that! The docs are not essential to the project anyway.

[Pietro Monticone]

I’ve also reported it here: #general > Why is doc-gen4 so slow? @ 💬

[Pietro Monticone]

Performance fix https://leanprover.zulipchat.com/#narrow/stream/113488-general/topic/Why.20is.20doc-gen4.20so.20slow.3F/near/526944691

[Rémy Degenne]

I've enabled docs generation again. Let's see if it's fast: https://github.com/RemyDegenne/brownian-motion/actions/runs/16046299057/job/45278364911

[Rémy Degenne]

It completed in 37 minutes. That's back to normal. :+1: