Hi Willy, > > Is there a similar mechanism in HAProxy? So far I can only see the > > static option for the initial window size which comes with the mentioned > > drawbacks. > > There is nothing similar. One of the problems H2 is facing is that there > can be application congestion anywhere in the chain. For example, let's > say a POST request is sent to a server subject to a maxconn and remains > in the queue for a few seconds. We definitely don't want to block the > whole connection during this time because we've oversized the window. > > And there's also the problem of not allocating too many buffers to each > stream, or it becomes a trivial DoS.
That makes sense, since we had to accommodate the use-case which triggered the investigation we increased the window size to 512k as a middle-ground. We don't usually see congestion on our HAProxies so we are hoping that this does not cause any other issues, we'll see once it hits prod. > However, as I mentioned somewhere (maybe the issue above, I don't remember), > I think that the vast majority of users are not downloading and uploading at > the same time over a same connection. Either they're uploading a large file > or downloading contents to be rendered. I agree, that seems to be the case for our scenarios. > That's something to think about. Thanks for re-heating this old topic! Thanks for taking the time to look into it! Regards Max
