Code speedup with Cython even when included in custom runtime, not happening

[Vipluv Aga]

I am running a flask app accessed by endpoints  on google app engine flex

There are certain modules that use shapely package of python. The exact same app and inputs on my local machine for a certain calculation take 36 seconds say, while once deployed on GAE it takes above 9 to 10 minutes.

First I thought that locally often the IDE converts packages to cython modules for speedups. I tried doing the same by converting the flex engine to custom runtime, and running a Dockerfile to build the Cython packages. 

My Dockerfile is as below

FROM gcr.io/google-appengine/python

LABEL python_version=python3.6

RUN virtualenv --no-download /env -p python3.6

# Set virtualenv environment variables. This is equivalent to running

# source /env/bin/activate

ENV VIRTUAL_ENV /env

ENV PATH /env/bin:$PATH

ADD requirements.txt /app/

RUN pip install --upgrade pip

RUN pip install -r requirements.txt

ADD . /app/

RUN python cythonsetup.py build_ext --inplace

CMD exec gunicorn -t 600 -c gunicorn.conf.py -b :$PORT main:app

My cythonsetup.py to build and include the cython builds

from setuptools import setup,Extension

#from Cython.Build import cythonize

from Cython.Distutils import build_ext

ext_modules = [

    Extension("addonModules.GridMakerCy", ["addonModules/GridMaker.py"], ),

    Extension("addonModules.GeoCoordtoMetersCy", ["addonModules/GeoCoordtoMeters.py"],)]

for e in ext_modules: 

    e.cython_directives = {"language_level": "3"}

setup(name='GridMaker',

      cmdclass = {'build_ext': build_ext},

      ext_modules = ext_modules,

      

      )

And i import the built cythons correctly (I confirmed the code gave an answer as I named the cython modules differently from python modules), however the calc time didnt change -- locally it takes very little time (even after including datastore and cloud storage read/writes--- which take longer on a local machine with gcloud clients) but in the app engine it takes very very long. 

I logged into the GAE instance itself, and

 after 

docker exec -it gaeapp /bin/bash

i confirmed that cython is installed. Then why is the run so slow?

[Manpreet Sidhu (Google Cloud Support)]

Thanks for reaching out. When Cython is slower, it can probably be pointed to type conversions. Here's a Stack Overflow post with a code speed test between Python and Cython.

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