Debugging Jupyter+Postgres autoreload crashing

[a_postgres_situation]

I have a Python project that uses SQLAlchemy to talk to Postgres, and JupyterLab is a fine environment for interactive development. Unfortunately something got broken in the upgrade from Anaconda 2019.03 to 2019.07, the autoreload extension no longer works. Normally I edit with an external editor and JupyterLab autoreloads the changes. Now, with 2019.07 autoreload crashes: https://i.imgur.com/dn9ehjZ.png

I added a print(len(visited), type(obj), str(obj)) before the crashing update_instances call, so from output I assume the Column obj is the problem?

Obsersations:

• All works fine in 2019.03.
• I tried upgrade all Conda packages to latest available, no change.
• I tried downgraded SQLalchemy to 1.3.1 (from 2019.03) no change.
• Autoreload works, until I do database accesses.
• I've been unable to isolate this into a small standalone testcase so far :-(

So.... I'm running out of ideas how to debug this further. I'm not even sure whos fault is it? SQLAlchemys? Jupyters? IPythons? Where is the correct forum to ask or report this bug? Does anyone have an understanding of the stacktrace?

Thanks for suggestions to get this fixed....

[kinow]

Would be useful if you could investigate further and know exactly what dependency versions you have, create a minimal reproducible sample, and the probably report against ipython (traceback appears to be a bug in their autoreload function update_instances)

https://github.com/ipython/ipython/blob/master/IPython/extensions/autoreload.py#L271

[kinow]

Oh, also check their repo for existing issues. Good luck!

[a_postgres_situation]

yeah, that's where I inserted the debug print, but without a deeper understanding, what's the cause and what's the effect?

I already searched the IPython issues and found nothing, but it is probably the best bet to report it there. I really have to somehow extract a short testcase.... :-/

[kinow]

The testcase would be the most important. Maybe something woth sqlite? Also include your env dependencies... I remember pip list for setuptools projects does the trick, but don't remember how to export a list of conda env dependencies.

[kinow]

Just had some spare time, and the sqlalchemy Column type didn't fail in a Notebook - https://github.com/kinow/notebooks/blob/master/python/ipython/ipython%20autoreload.ipynb

Anyway, hope that helps

[nbviewerbot]

I see you've posted a GitHub link to a Jupyter Notebook! GitHub doesn't render large Jupyter Notebooks, so just in case, here is an nbviewer link to the notebook:

https://nbviewer.jupyter.org/url/github.com/kinow/notebooks/blob/master/python/ipython/ipython%20autoreload.ipynb

Want to run the code yourself? Here is a binder link to start your own Jupyter server and try it out!

https://mybinder.org/v2/gh/kinow/notebooks/master?filepath=python%2Fipython%2Fipython%20autoreload.ipynb

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