Exceptions not handled properly in the proxy's AsyncTunnelHTTPConnection leading to the leaks and pool starvation

[janosik47]

The problem is described in #921

I made a proposal how to fix it in a comment

[rail-chamidullin-myriad]

@janosik47 I am dealing exactly with the same issue and I got to the same conclusion as you. Any update on this? Is there some PR with the fix?

[janwijbrand]

FWIW to move forward on this issue, I opted for a monkey patch in my code base. Hopefully only temporary. The monkey patch looks more or less like this:

_original_handle_async_request = AsyncTunnelHTTPConnection.handle_async_request

@functools.wraps(_original_handle_async_request)
async def _patched_handle_async_request(self, request):
    """Wrapper around ``handle_async_request`` that cleans up the inner
    connection when a tunnel setup error (e.g. TLS handshake failure)
    leaves it as a zombie.
    """
    try:
        return await _original_handle_async_request(self, request)
    except BaseException:
        if not self._connected and not self._connection.is_closed():
            with AsyncShieldCancellation():
                await self._connection.aclose()
        raise

def apply():
    if (
        AsyncTunnelHTTPConnection.handle_async_request
        is not _patched_handle_async_request
    ):
        AsyncTunnelHTTPConnection.handle_async_request = (
            _patched_handle_async_request
        )