Connection aborted after HttpParserInvalidMethodError when making consecutive POST requests

Checklist

• The bug is reproducible against the latest release or master.
• There are no similar issues or pull requests to fix it yet.

Describe the bug

After making a few POST requests, one of the requests ends with the connection aborted. The server logs a log about an invalid HTTP method, however only POST method is consistently attempted.

Steps to reproduce the bug

The bug is reproduced when making multiple requests.posts against a service running with latest uvicorn

Unfortunately I was not able to create a reliable reproduction, as running locally I seemed to make successful requests

Expected behavior

All the requests used to pass in sequence without errors

Actual behavior

One of the requests, after an inconsistent number of successful requests, fails with a connection error after sending the request. The server logs

Debugging material

Request aborted

  File "/usr/local/lib/python3.10/site-packages/requests/api.py", line 117, in post
    return request('post', url, data=data, json=json, **kwargs)
  File "/usr/local/lib/python3.10/site-packages/requests/api.py", line 61, in request
    return session.request(method=method, url=url, **kwargs)
  File "/usr/local/lib/python3.10/site-packages/requests/sessions.py", line 529, in request
    resp = self.send(prep, **send_kwargs)
  File "/usr/local/lib/python3.10/site-packages/requests/sessions.py", line 645, in send
    r = adapter.send(request, **kwargs)
  File "/usr/local/lib/python3.10/site-packages/requests/adapters.py", line 501, in send
    raise ConnectionError(err, request=request)
requests.exceptions.ConnectionError: ('Connection aborted.', RemoteDisconnected('Remote end closed connection without response'))

Server warning (uvicorn.error).

"Invalid HTTP request received."
Traceback (most recent call last):
  File "/usr/local/lib/python3.10/site-packages/uvicorn/protocols/http/httptools_impl.py", line 132, in data_received
    self.parser.feed_data(data)
  File "httptools/parser/parser.pyx", line 212, in httptools.parser.parser.HttpParser.feed_data
httptools.parser.errors.HttpParserInvalidMethodError: Invalid method encountered

Environment

• Running uvicorn 0.17.1 with CPython 3.10.1 on Linux
• Encountered with Kubernetes services, without reverse proxy/ingress

Additional context

Since requests library is using a keepalive for the requests, a suspect change is the recent https://github.com/encode/uvicorn/pull/1332, and reverting uvicorn version seems to make the problem go away.

[tomchristie]

Now resolved in 0.17.2 - https://github.com/encode/uvicorn/pull/1356

[Kludex]

The solution I propose is to revert both. PRs were created:

• https://github.com/encode/uvicorn/pull/1354
• https://github.com/encode/uvicorn/pull/1355 (branch on top of the above)

Both memory leak and this issue are solved with my proposal.