HOOMD cache does not seem to work as expected

[mphoward]

The caching mechanism in unit-test.yaml isn't working as I would expect in our component. The first time the workflow runs on a PR, there is a cache miss, HOOMD builds, and is successfully stored, e.g.,:

https://github.com/mphowardlab/azplugins/actions/runs/12917804952/job/36025002876

like I would expect. However, after I push another commit to the PR branch, a cache miss is still reported so HOOMD gets built again, but now a warning is raised because the cache key already exists!

https://github.com/mphowardlab/azplugins/actions/runs/12920560098/job/36033082022

It seemed like the intent of caching was that the base build of HOOMD would persist within a PR if not across all workflow runs. Right now, we are spending ~30 minutes rebuilding HOOMD on every PR commit... any ideas what's going on here? Are you able to reproduce the same issue in your repo?

[joaander]

It seemed like the intent of caching was that the base build of HOOMD would persist within a PR if not across all workflow runs.

Yes. Practically this is limited to a single PR due to cache scoping and a short expiration time.

Right now, we are spending ~30 minutes rebuilding HOOMD on every PR commit... any ideas what's going on here? Are you able to reproduce the same issue in your repo?

The cache was working when I originally implemented it, but it no longer functions. Many users of action/cache have the same problem when using actions/cache within a container:

actions/cache#1361 (comment)
actions/cache#1169
actions/cache#1300
actions/cache#1400
actions/cache#1455

I have attempted many of these workarounds and was still not able to fix the problem (see e.g. #9, #12). GitHub has been silent on the issue. The only commits to action/cache in years have been documentation updates surrounding the removal of v2 (which doesn't have this issue) and small spelling fixes in the docs.

[mphoward]

sigh Thanks for the explanation. For now, we will disable building HPMC to save time since we don't need it for our component. Hopefully GitHub implements a fix for this.