ref(gunicorn): use gaiohttp workers

[mboersma]

Summary of Changes

Replaces the default sync gunicorn worker class with gaiohttp. This async worker class is based on aiohttp for Python 3. It may offer better responsiveness and lower CPU load.

My preliminary testing shows it holds up well and uses less CPU, but I'll produce more specific benchmark results to justify this soon.

TODO:

• produce more specific benchmark results
• continue long-term testing to reassure myself about stability of this change

Testing Instructions

There are no specific testing instructions, since this should be an invisible backend change. However, monitoring for response times and CPU load over a long period of time would assure this does not introduce new problems.

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[mention-bot]

By analyzing the blame information on this pull request, we identified @helgi and @kmala to be potential reviewers

[bacongobbler]

• Supports both client and server Web-Sockets out-of-the-box.

This could be game changing. We've been looking for a websocket-compatible HTTP server that works with django for a while. This could mean that we could potentially support deis logs -f, right?

[helgi]

Should be able to, tho the alternative could have always been to have a logger endpoint (public) we could pass on the connection to the end user which could allow for it instead of piping via the API

[jgmize]

While benchmarking, it might be interesting to also try out https://github.com/MagicStack/uvloop via the implementation in aio-libs/aiohttp#878. See http://magic.io/blog/uvloop-blazing-fast-python-networking/ for some existing benchmarks.

[codecov-io]

Current coverage is 86.57%

Merging #794 into master will decrease coverage by 0.07%

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Powered by Codecov. Last updated by 4974584...16b326a

[mboersma]

it might be interesting to also try out https://github.com/MagicStack/uvloop...

I did spend some time using the KeepSafe/aiohttp tip and trying to get it working as advertised, but ran into a variety of configuration issues I couldn't get past. I love the benchmarking numbers on uvloop, so let's revisit this when it's had time to mature. Hopefully just this gaiohttp change will help.

[mboersma]

This seems promising, especially when paired with the potential of uvloop. But my boom and workflow-e2e test benchmarks have shown it doesn't perform quite as well as the trusty gunicorn sync worker.

So I'm closing this, but it would be smart for someone to revisit this territory in the future after #833 or #835 are (probably) merged.