Long import time

What is your issue?

Importing the xarray package takes a significant amount of time. For instance:

❯ time python -c "import xarray"
python -c "import xarray"  1.44s user 0.52s system 132% cpu 1.476 total

compared to others

❯ time python -c "import pandas"
python -c "import pandas"  0.45s user 0.35s system 177% cpu 0.447 total

❯ time python -c "import scipy"
python -c "import scipy"  0.29s user 0.23s system 297% cpu 0.175 total

❯ time python -c "import numpy"
python -c "import numpy"  0.29s user 0.43s system 313% cpu 0.229 total

❯ time python -c "import datetime"
python -c "import datetime"  0.05s user 0.00s system 99% cpu 0.051 total

I am obviously not surprised that importing xarray takes longer than importing Pandas, Numpy or the datetime module, but 1.5 s is something you clearly notice when it is done e.g. by a command-line application.

I inquired about import performance and found out about a lazy module loader proposal by the Scientific Python community. AFAIK SciPy uses a similar system to populate its namespaces without import time penalty. Would it be possible for xarray to use delayed imports when relevant?

[headtr1ck]

Nice. Does it work on python 3.8?

according to the docu it exists since 3.4.

[eendebakpt]

Some other projects are considering lazy imports as well: https://scientific-python.org/specs/spec-0001/