html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/issues/3668#issuecomment-573509747,https://api.github.com/repos/pydata/xarray/issues/3668,573509747,MDEyOklzc3VlQ29tbWVudDU3MzUwOTc0Nw==,2443309,2020-01-13T05:06:45Z,2020-01-13T05:06:45Z,MEMBER,"@dmedv and @rabernat - after thinking about this a bit more and reviewing the links in the last post, I'm pretty sure we're bumping into a bug in zarray's directory store pickle support. It would be nice to confirm this with some zarr-only tests but I don't see why the store needs to reference the zgroup files when the object is unpickled.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,546562676
https://github.com/pydata/xarray/issues/3668#issuecomment-573197896,https://api.github.com/repos/pydata/xarray/issues/3668,573197896,MDEyOklzc3VlQ29tbWVudDU3MzE5Nzg5Ng==,2443309,2020-01-10T20:43:30Z,2020-01-10T20:43:30Z,MEMBER,"Also, @dmedv, can you add the output of `xr.show_versions()` to your original post?","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,546562676
https://github.com/pydata/xarray/issues/3668#issuecomment-573196874,https://api.github.com/repos/pydata/xarray/issues/3668,573196874,MDEyOklzc3VlQ29tbWVudDU3MzE5Njg3NA==,2443309,2020-01-10T20:40:14Z,2020-01-10T20:40:14Z,MEMBER,"> The scenario you are describing--trying to open a file that is not accessible at all from the client--is certainly not something we ever considered when designing this. It is a miracle to me that it does work with netCDF.

True. I think its fair to say that the behavior you are enjoying (accessing data that the client cannot see) is the exception, not the rule. I expect there are many places in our backends that will not support this functionality at present.

The motivation for implementing the `parallel` feature was simply to shard the fileIO time when opening large collections (>10k) of netcdf files.

Ironically, this dask issue also popped up and has some significant overlap here: https://github.com/dask/dask/issues/5769

In both of these cases, the desire is for the worker to open the file (or zarr dataset), construct the underlying dask arrays, and return the meta object. This requires the object to be fully pickle-able and for any references to be maintained. It is possible, as indicated by your traceback, that the zarr backend is trying to reference the `zgroup` file and its not there. The logical place to start would be to look into why we can't pickle xarray datasets that come from zarr stores. ","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,546562676