reduce_python_lambda.md

Advice on how to reduce code size

There are use cases where you need to reduce the total size of your python deployed code including library code.

E.g:

I have to deploy a layer with pandas and numpy etc. Total size cannot be over 260mb.

Using pre compiled python files

One way is to compile python with python3 -m compileall -b. and then remove all the *.py source files.

Don't do this on your source directory, but copy it to a different location e.g dist/

What I do is, copy the python pip packages into the dist folder, and then I run compileall. After this find dist -iname "*.py" -exec rm {} \; to delete all source files.

The result is:

• smaller distribution size
• faster startup

Why does this work:

Python loads *.py files, if a *.pyc file exists, it will load the *.pyc file, there's a bit more to it, but I won't go into the details.

If only a *.pyc file exists, and no source file, python will still load the file. This means you can run completely of precompiled python files.