Update fsspec minimal version?

[joshmoore]

I've just gotten this user report:

    cdatas = self.chunk_store.getitems(ckeys, on_error="omit")
  File "c:\users\c\napari\lib\site-packages\zarr\storage.py", line 1085, in getitems
    return self.map.getitems(keys, on_error="omit")
AttributeError: 'FSMap' object has no attribute 'getitems'

(napari) PS C:\Users\callan> pip show zarr
Name: zarr
Version: 2.8.1
Summary: An implementation of chunked, compressed, N-dimensional arrays for Python.
Home-page: https://github.com/zarr-developers/zarr-python
Author: None
Author-email: None
License: MIT
Location: c:\users\callan\napari\lib\site-packages
Requires: numcodecs, fasteners, asciitree, numpy
Required-by: ome-zarr, omero-napari

Is it possible that we need to (A) update the fsspec pin and (B) perhaps include it as a requirement?

requirements_dev_optional.txt:fsspec==0.8.4; python_version > '3.6'

cc: @martindurant

[martindurant]

fsspec is a pretty small requirement, since it has no deps of its own, but many zarr users won't need it.
For an optional requirement, yes I would update. 0.9.0 includes getitems, but why not just keep up with latest.

[joshmoore]

but why not just keep up with latest.

Sorry, I didn't mean pin, but rather set a minimal version. 👍 for going >= 0.9.0. If there are other votes for dropping optional, speak up.

[joshmoore]

Oh dear. This may end up being something of a can-of-worms. All of the versions in requirements_dev_optional.txt are pinned, and I imagine they haven't been updated since appveyor was dropped in gh-706. The activation of dependabot (gh-734) should kick off the process again.

[MatthewBM]

I'm having stability issues with both fsspec<=0.8.0 and fsspec>=0.9.0. Only fsspec == 0.8.7 is working for me currently using Zarr and S3

fsspec<=0.8.0 cannot import maybe_sync:
https://www.gitmemory.com/issue/intake/filesystem_spec/597/829392517

 from fsspec.asyn import AsyncFileSystem, sync, sync_wrapper, maybe_sync
ImportError: cannot import name 'maybe_sync'

fsspec>=0.9.0 cannot use on_error because fsspec's map operator no longer takes on_error arg
awslabs/amazon-asdi#21

~/anaconda3/envs/satpy/lib/python3.7/site-packages/zarr/core.py in _chunk_getitems()
   1689 
   1690         ckeys = [self._chunk_key(ch) for ch in lchunk_coords]
-> 1691         cdatas = self.chunk_store.getitems(ckeys, on_error="omit")
   1692         for ckey, chunk_select, out_select in zip(ckeys, lchunk_selection, lout_selection):
   1693             if ckey in cdatas:

TypeError: getitems() got an unexpected keyword argument 'on_error'

[martindurant]

I don't think there would be any downside to depending on very recent fsspec

[joshmoore]

Ok. I've activated dependabot (#734) which will have us testing with newer versions, but is there any way to give guidance to users on these dependencies, @martindurant?

[martindurant]

It's only fairly recently that this functionality got into zarr anyway, with previous docs describing how to make your own mapper from fsspec itself - so I'm not to worried about that.

[joshmoore]

@MatthewBM are things working again?

[joshmoore]

I'm leaning towards closing this based on #734 since we should be able to detect when a new version of fsspec* breaks things.

But that won't necessarily help users to know when they need to update. Allowing pip install zarr[fsspec] with the right minimal version might be one way to distribute this knowledge. Any opinions?