dask: ReadTheDocs PR builds are failing

I saw this pop up in my notifications and was like oh god what have we broken now?! 😆

Thanks for looking into this @choldgraf!

I also think it might be easy to get a quick speed up in the pydata theme, will see if my hunch is correct today

Just a note that we recently got a little numfocus grant to work on the pydata theme, so I suspect improving performance will be something that happens once that gets rolling

Ok i think i figured out a way to selectively remove navigation entries so that you can still autogenerate API docs with stub pages, but not have them show up in the navigation bar. Can you try adding the function here to your docs build and see if that fixes the speed issues? https://github.com/pydata/pydata-sphinx-theme/pull/492/files#diff-381cb883eeefc0f20f80b41392b657f8a6f8c12dc106954c84ed0c7402e37c64R475

In that case my vote would be to either ask or pay for our build times to be increased 😃

tl;dr: Looks like there were no changes in Dask that produced this slowdown, but somehow the newer dask-sphinx-theme seems to make a huge difference. The solution for now is to set dask-sphinx-theme>=1.3.5,<2 in docs/requirements-docs.txt.

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I launched two builds on https://github.com/astrojuanlu/dask/pull/1, one for 049d803 (which passed 3 days ago) and another one for ba29ba3, which failed 2 days ago. They got built on our large builders so they passed - but they took ~1400 seconds, whereas main used to take ~400 seconds.

This step:

 /home/docs/checkouts/readthedocs.org/user_builds/dask/envs/latest/bin/python -m sphinx -T -E -b html -d _build/doctrees -D language=en . _build/html 

took 200 seconds on the good build, and

 /home/docs/checkouts/readthedocs.org/user_builds/dask-astrojuanlu/envs/latest/bin/python -m sphinx -T -b html -d _build/doctrees -D language=en . _build/html 

took 1140 s on the bad build. Therefore, there were no code changes in Dask that produced this slowdown.

The only relevant difference in dependencies I saw was dask-sphinx-theme-1.3.6 vs dask-sphinx-theme-2.0.0. So I went ahead and pinned it, and that seemed to do the trick. https://readthedocs.org/projects/dask-astrojuanlu/builds/14928907/ took less than 400 seconds. Therefore, for now the solution is

From d67dfdc161bec6ee5e02341a590e0f5e0de173d9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Luis=20Cano=20Rodr=C3=ADguez?= <hello@juanlu.space>
Date: Thu, 7 Oct 2021 11:57:11 +0200
Subject: [PATCH] Try capping dask-sphinx-theme

---
 docs/requirements-docs.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/requirements-docs.txt b/docs/requirements-docs.txt
index cedb3ecd06..52e69cb6cf 100644
--- a/docs/requirements-docs.txt
+++ b/docs/requirements-docs.txt
@@ -1,6 +1,6 @@
 numpydoc
 sphinx>=4.0.0
-dask-sphinx-theme>=1.3.5
+dask-sphinx-theme>=1.3.5,<2
 sphinx-click
 toolz
 cloudpickle

Most importantly, the “excessive memory consumption” is misleading: the builds are failing because of timeout.

The last passing build of main appears to be https://readthedocs.org/projects/dask/builds/14901502/, which took half the time it’s taking now. Suspicious.

I’ll inspect this more closely in the coming hours.