uWSGI is still pretty great, actually

I've used uWSGI for a long time but newer Python web servers have come along. Let's compare uWSGI to uvicorn with the all-important "hello, world" style program. I yield the body in pieces instead of sending back the whole body at once to include some context switching overhead.

I've also been working on an experimental PyPy + ASGI plugin for uWSGI. Let's see if the performance is in the right ballpark.

I'm using hey -z 8s http://localhost to send some requests to the app.

WSGI:

import sys
import pprint


def application(env, start_response):
    start_response("200 OK", [("Content-Type", "text/html")])
    results = [
        b"<pre>",
        b"Hello World\n",
        sys.executable.encode("utf-8"),
        b" ",
        pprint.pformat(env),
        b"</pre>",
    ]

    for result in results:
        if isinstance(result, str):
            result = result.encode("utf-8")
        yield result

ASGI:

import sys
import pprint


def results(scope):
    results = [
        b"<pre>",
        b"Hello World\n",
        sys.executable.encode("utf-8"),
        b" ",
        pprint.pformat(scope),
        b"</pre>",
    ]

    for result in results:
        if isinstance(result, str):
            result = result.encode("utf-8")
        yield result


async def application(scope, receive, send):
    await send(
        {
            "type": "http.response.start",
            "status": 200,
            "headers": [[b"content-type", b"text/html"],],
        }
    )
    for result in results(scope):
        await send({"type": "http.response.body", "body": result, "more_body": True})

    await send({"type": "http.response.body", "body": result, "more_body": False})

WSGI, Python 3.8 and standard uWSGI Python plugin: uwsgi --plugin python --wsgi minimal --http [::]:80 --enable-threads --disable-logging --listen 4096

Summary:
  Total:    8.0239 secs
  Slowest:  0.0306 secs
  Fastest:  0.0057 secs
  Average:  0.0231 secs
  Requests/sec: 2157.3084


Response time histogram:
  0.006 [1] |
  0.008 [1] |
  0.011 [1] |
  0.013 [2] |
  0.016 [8] |
  0.018 [10]    |
  0.021 [12]    |
  0.023 [10728] |■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
  0.026 [6388]  |■■■■■■■■■■■■■■■■■■■■■■■■
  0.028 [95]    |
  0.031 [64]    |

WSGI, Python 3.8, uvicorn --host 0.0.0.0 --port 80 --interface wsgi minimal:application --workers 1 --backlog 4096 --no-access-log

Summary:
  Total:    8.0296 secs
  Slowest:  0.0939 secs
  Fastest:  0.0092 secs
  Average:  0.0461 secs
  Requests/sec: 1080.8754


Response time histogram:
  0.009 [1] |
  0.018 [197]   |■■■■■
  0.026 [732]   |■■■■■■■■■■■■■■■■■■■
  0.035 [1490]  |■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
  0.043 [1454]  |■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
  0.052 [1408]  |■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
  0.060 [1542]  |■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
  0.068 [1129]  |■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
  0.077 [591]   |■■■■■■■■■■■■■■■
  0.085 [96]    |■■
  0.094 [39]    |■

ASGI, Python 3.8, uvicorn --host 0.0.0.0 --port 80 minimalasgi:application --workers 1 --backlog 4096 --no-access-log

Summary:
  Total:    8.0146 secs
  Slowest:  0.0450 secs
  Fastest:  0.0051 secs
  Average:  0.0221 secs
  Requests/sec: 2258.2405


Response time histogram:
  0.005 [1] |
  0.009 [11]    |
  0.013 [349]   |■
  0.017 [58]    |
  0.021 [1049]  |■■■
  0.025 [16560] |■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
  0.029 [43]    |
  0.033 [8] |
  0.037 [8] |
  0.041 [10]    |
  0.045 [2] |

ASGI version, PyPy 3.6.9 and experimental plugin:

Summary:
  Total:    8.0430 secs
  Slowest:  0.0757 secs
  Fastest:  0.0077 secs
  Average:  0.0460 secs
  Requests/sec: 1081.9301


Response time histogram:
  0.008 [1] |
  0.014 [5] |
  0.021 [6] |
  0.028 [7] |
  0.035 [8] |
  0.042 [14]    |
  0.048 [7824]  |■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
  0.055 [164]   |■
  0.062 [69]    |
  0.069 [147]   |■
  0.076 [457]   |■■

WSGI version, PyPy 3.6.9 and experimental plugin:

Summary:
  Total:    8.0179 secs
  Slowest:  0.0396 secs
  Fastest:  0.0022 secs
  Average:  0.0187 secs
  Requests/sec: 2660.7978


Response time histogram:
  0.002 [1] |
  0.006 [3] |
  0.010 [13]    |
  0.013 [17]    |
  0.017 [108]   |
  0.021 [20001] |■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
  0.025 [352]   |■
  0.028 [105]   |
  0.032 [146]   |
  0.036 [318]   |■
  0.040 [270]   |■

I thought it was pretty interesting that uWSGI and uvicorn's WSGI / ASGI performance is flipped: in this test uWSGI's WSGI speed is about the same as uvicorn's ASGI speed. The WSGI mode in uvicorn also shows a greater spread of response times than the others.

The experimental plugin is written almost entirely in Python. It hasn't been optimized yet but it performs well in WSGI mode. A lot of things might be done to improve its ASGI mode.