Locking bug? AttributeError: 'NoneType' object has no attribute 'lock_release'

[cisaacstern]

In running recipes on Pangeo Forge Cloud, we've encountered a few locking-related errors recently.

• Diagnosing first deployment failure noaa-coastwatch-geopolar-sst-feedstock#2 (comment)
• Add new instance id cmip6-feedstock#2 (comment)
• Use dict object cmip6-feedstock#4 (comment) ➡️ https://pangeo-forge.org/dashboard/recipe-run/152

Based on @rabernat's linked comment on the first of these issues, it seems there are certain combinations of inputs_per_chunk/target_chunks kwargs which may cause and/or resolve this issue. Perhaps it's possible to catch these in XarrayZarrRecipe.__post_init__ and fail fast, ideally with a recommendation for the user?

As noted in pangeo-forge/user-stories#7, I haven't succeeded in reproducing this error outside of Pangeo Forge Cloud, since it seems it's either dependent on (a) the number of distributed workers; and/or (b) is intermittent.

[cisaacstern]

Post 0.10.0 release, this is no longer relevant.