TypeError: backoff.on_exception when running in uvicorn

[dj0nes]

Describe the bug
I noticed the following error when trying to use launch darkly in a fastapi project with code reloading:

TypeError: backoff.on_exception applied to a regular function inside coroutine, this will lead to event loop hiccups. Use backoff.on_exception on coroutines in asynchronous code.

The error is thrown from this line in python-server-sdk.

The command to run uvicorn is here in the base image.

To reproduce
I created a simple repo to reproduce the issue.

git clone https://github.com/dj0nes/ldclient-uvicorn-issue.git
docker-compose up

Expected behavior
The application should run without crashing.

SDK version
launchdarkly-server-sdk~=6.11.1

Language version, developer tools
python 3.7

OS/platform
alpine 3.8

[bwoskow-ld]

Hi @dj0nes,

Thanks for letting us know about this issue. I have to admit, prior to this issue I had never heard of uvicorn. Our team here is unfamiliar with it. As such, we don't currently claim compatibility with uvicorn.

After some investigation I found that the backoff package used by our Python SDK has an open issue to address the uvicorn incompatibility. That issue currently has an open question about steps to reproduce the issue -- perhaps you can chime in there. Once that issue is addressed in a new release, we can look into bumping our Python SDK to the newer package version.

We're on a bit of an old backoff version right now (1.4.3 from two and a half years ago) and I don't know what else lurks in between our version and an upcoming version. As such we can't guarantee that we'll be able to update-- for example, newer backoff versions might drop compatibility with Python versions which our SDK still supports. Yet, we can consider it once available. If you're up for it, when a new backoff version is available, you can submit a pull request to this repository to apply the fix.

Cheers,
Ben

[dj0nes]

Hi Ben, thanks for looking into the issue! I'll see if I can help on the backoff issue you mentioned, and open a PR here if they can get a fix out.

Closing this for now.

[dj0nes]

Good news! I no longer see this error, and have updated the example repo to demonstrate it working.

I'm not sure what changed, but thanks again for your help!