From: Junio C Hamano Date: Thu, 02 Apr 2015 22:58:50 GMT Subject: Re: [PATCH] protocol upload-pack-v2 Message-ID: In-Reply-To: <1935847.zk75T7vt7M@mfick1-lnx> Martin Fick writes: >> The current protocol has the following problems that limit >> us: >> >> - It is not easy to make it resumable, because we >> recompute every time. This is especially problematic for >> the initial fetch aka "clone" as we will be talking about >> a large transfer. Redirection to a bundle hosted on CDN >> might be something we could do transparently. >> >> - The protocol extension has a fairly low length limit. >> >> - Because the protocol exchange starts by the server side >> advertising all its refs, even when the fetcher is >> interested in a single ref, the initial overhead is >> nontrivial, especially when you are doing a small >> incremental update. The worst case is an auto-builder >> that polls every five minutes, even when there is no new >> commits to be fetched. > > A lot of focus about the problems with ref advertisement is > about the obvious problem mentioned above (a bad problem > indeed). I would like to add that there is another related > problem that all potential solutions to the above problem do > not neccessarily improve. When polling regularly there is > also no current efficient way to check on the current state of > all refs. It would be nice to also be able to get an > incremental update on large refs spaces. Yes, incremental ref update is an important problem to solve. I think one potential solution was indeed mentioned to improve that exact issue, e.g. footnote #3 in $gmane/264000.