Issuing requests in close concurrency can unneccessarily result in multiple HTTP/2 connections.

When I do several requests with the AsyncClient it seems that it opens multiple connections to the server. My code looks like this:

async def _send_request(self, client, image, url):
    headers = {
        'Content-Type': 'image/jpeg',
        'Content-Length': str(len(image))
    }
    return await client.post(
        url,
        headers=headers,
        data=image
    )

async with httpx.AsyncClient(timeout=timeout, base_url=self.server_url) as client:
    requests = []
    for image in images:
        requests.append(self._send_request(client, image, url))
    responses = await asyncio.gather(*requests)

As far as I understand it should use a connection pooling, store the connection and reuse it. In my case I get the following debug message for every image- post request I send with a loop:

DEBUG:httpx.dispatch.connection:start_connect host='api.garaza.io' port=443 timeout=TimeoutConfig(connect_timeout=None, read_timeout=60, write_timeout=5)

Am I doing anything wrong or is it a bug?

[yeraydiazdiaz]

I noticed this happening on a similar situation as well and it also confused me. I fully expected connections to only be created once per origin, but it seems the current behaviour is by design according to this test?

https://github.com/encode/httpx/blob/master/tests/dispatch/test_connection_pools.py#L69-L80

@PrimozGodec, max_connections is a BoundedSemaphore which HTTPX uses to limit the number of connections of the pool. The default is 100.

[ojii]

But, we don’t know ahead of time if a connection will be HTTP/1.1 or HTTP/2 until it’s been established.

is there a way around this issue if we know beforehand that it’s http2 (as in, when talking to a server that is http2 only, such as APNS)?