Deprecated autoclose option

[pwolfram]

In updated versions of xarray we are getting a deprecation error for autoclose, e.g., at MPAS-Dev/MPAS-Analysis#501.

A look through the issues is not transparent as to this reason and this issue is to collect the high-level information on this change.

Is there an alternative use that should be considered instead?

[jhamman]

@pwolfram - this option was deprecated in the last release following #2261. Xarray now uses a LRU cache to manage open file handles. This can be configured via a global option: xarray.set_options(file_cache_maxsize=...).

If I recall correctly, you were part of the early LRU cache conversations.

release notes on the subject: http://xarray.pydata.org/en/stable/whats-new.html#breaking-changes

[pwolfram]

@jhamman, LRU is much better. The api-change on our size is to replace autoclose=True with file_cache_maxsize=A_REASONABLE_BIG_NUMBER, correct?

[jhamman]

@pwolfram - Thats right. We currently default to a fairly small number (128):

xarray/xarray/core/options.py

Line 18 in 3ae93ac

FILE_CACHE_MAXSIZE: 128,

[pwolfram]

Thanks @jhamman! @xylar, I'm thinking file_cache_maxsize=1200 would be a good default (100 years of monthly files) that could be modified via the config files we use.