ray docker images do not have uvloop installed

[fkaleo]

It looks like uvloop is not a dependency of uvicorn but only of uvicorn[standard as per the documentation of uvicorn:

$ pip install uvicorn

This will install uvicorn with minimal (pure Python) dependencies.

$ pip install uvicorn[standard]

This will install uvicorn with "Cython-based" dependencies (where possible) and other "optional extras".

In this context, "Cython-based" means the following:

the event loop uvloop will be installed and used if possible.

https://www.uvicorn.org/#quickstart

Originally posted by @fkaleo in #9216 (comment)

[fkaleo]

I could verify this on Docker image rayproject/ray:1.12.1-py39 with:
python -c "import uvloop"

[fkaleo]

This is a "new" behaviour of uvicorn since august 2020 introduced in release 0.12.0 by encode/uvicorn#666

[mwtian]

Looks you have a pending PR for this. Thanks for making the contribution!

[fkaleo]

Fix was reverted by #25530

[fkaleo]

@simon-mo can we reponen?