New httpcore stubs (v8.0+) cause httpx to eventually run out of connections

[warhammerkid]

Description

If you do not close real_response.stream then httpcore does not detect that the connection is free for reuse, and eventually you run out of available connections.

Detail

vcrpy/vcr/stubs/httpcore_stubs.py

Lines 135 to 137 in 9b58663

	# Reading the response stream consumes the iterator, so we need to restore it afterwards
	real_response_content = b"".join([part async for part in real_response.stream])
	real_response.stream = ByteStream(real_response_content)

The above code reads from the stream, but never calls aclose which is responsible for releasing the connection back to the pool for reuse.

The httpx library would normally take care of that for us, because it naturally closes responses after they're completely read. However, because we're replacing the async stream with a ByteStream here, that original aclose is never called.

[seowalex]

Hi, that was my change and apologies for this bug. Do you have a minimal reproducible example so that I can make sure it's fixed?

[warhammerkid]

Here's a test to reproduce this:

def test_connection_limit(tmpdir, httpbin):
    """Ensure that requests work with connection limits, i.e. streams are properly closed."""
    url = httpbin.url + "/get"
    limits = httpx.Limits(max_connections=1)

    with vcr.use_cassette(str(tmpdir.join("connection_limit.yaml"))):
        with DoAsyncRequest(limits=limits) as client:
            response1 = client("GET", url)
            response2 = client("GET", url)
            assert response1.status_code == 200
            assert response2.status_code == 200

When I use do_request the test variant that uses DoSyncRequest() doesn't work, and I did not look into why that might be.

[seowalex]

Thank you for the straightforward MRE. I can reproduce this, and have fixed it in https://github.com/seowalex/vcrpy. Could you give my fork a try and let me know if it solves your issue?

The exact fix is seowalex@2994f66.

[warhammerkid]

Yes, your fork does solve my issue. Thanks!