Make imports faster?

[chaithyagr]

For now imports seem really slow, make it faster for faster debug cycles

[paquiteau]

Are you still facing this issue ?

[paquiteau]

So I am facing this issue now (using multiprocessing) I have made some basic profiling using tuna for the visualization.

As we can see, the loading time is mostly due to external libraries (torch, sigpy, matplotlib and sigpy) are in the top three.

However, after this initial import there is no extra cost (import are cached internally by python)

Several possibilities:

• use import statements inside functions
• use some lazy import modules:
  • https://github.com/telekom/lazy-imports (useb by scikit-image)
  • https://github.com/noahmorrison/limp (very minimalistic)
  • https://pypi.org/project/apipkg/ (used by pytest)
• Do some manual crafting like here
• a decorator approach: https://stackoverflow.com/a/70583037/16019838

Related stuff:
https://stackoverflow.com/questions/4177735/best-practice-for-lazy-loading-python-modules
https://wiki.python.org/moin/PythonSpeed/PerformanceTips#Import_Statement_Overhead

Reproducing the profiling:

python -X importtime -c "import mrinufft"  2> import.log
tuna import.log