On Mon, Jan 21, 2019 at 11:45:20AM +0530, Kaartic Sivaraam wrote: > I recently came across a blog[1] about how protocol v2 speeds up the > transfer between the client and the server. It states that the amount > of data transmitted between the client and the server is less when > using the protocol v2. Yes, but... > # Git version: 2.19.0 > $ GIT_TRACE_PACKET=1 git -c protocol.version=2 ls-remote > git@xxxxxxxxxx:gitlab-org/gitlab-ce.git master > 2>git_protocol_2_git_2.19.0_stderr.txt > d4d4ebadfb373518013382560b1f505eb6217f13 refs/heads/master > > $ wc -l > 22 git_protocol_2_git_2.19.0_stderr.txt > > > # Git version: 2.20.0 > $ GIT_TRACE_PACKET=1 git -c protocol.version=2 ls-remote > git@xxxxxxxxxx:gitlab-org/gitlab-ce.git master > 2>git_protocol_2_git_2.20.0_stderr.txt > d4d4ebadfb373518013382560b1f505eb6217f13 refs/heads/master > 04845fdeae75ba5de7c93992a5d55663edf647e0 > refs/remotes/remote_mirror_630f74462b3b08a952486da866d5e702/master > 04845fdeae75ba5de7c93992a5d55663edf647e0 > refs/remotes/remote_mirror_655ad545056a2ad17e7ebc5461a986e4/master > d4d4ebadfb373518013382560b1f505eb6217f13 > refs/remotes/remote_mirror_d612bbe5bee4fbc624df371bc7caa759/master > > $ wc -l git_protocol_2_git_2.20.0_stderr.txt > 160971 git_protocol_2_git_2.20.0_stderr.txt v2.19, etc, were buggy. The rules for ls-remote's pattern matching do not permit us to use ref prefixes (because the documentation specifies that it matches "master" at the end of _any_ ref, not just in the usual spots). But we did anyway. The fix is in 631f0f8c4b (ls-remote: do not send ref prefixes for patterns, 2018-10-31). That should explain the extra refs, as well (they all match "master", too, and it was wrong that v2.19 did not show them). It's rather unfortunate, since otherwise ls-remote makes for a nice test of the advertisement code. ;) You can see some difference with "ls-remote --heads", as explained in 6a139cdd74 (ls-remote: pass heads/tags prefixes to transport, 2018-10-31). The best test is to do a noop git-fetch. E.g.: # just make sure we have all the objects. You still see the benefit # without it, but if you really want to count bytes, it makes sure # you're comparing apples to apples. git fetch # this has a big useless ref advertisement GIT_TRACE_PACKET=$PWD/v0 git -c protocol.version=0 fetch origin master # and this is much smaller. Unfortunately it's not just a single line # (for "master"), because tag-following requires that the other side # tell us about tags, too. GIT_TRACE_PACKET=$PWD/v2 git -c protocol.version=2 fetch origin master # this one is really tiny GIT_TRACE_PACKET=$PWD/v2-notags git -c protocol.version=2 fetch --no-tags origin master With my origin as https://github.com/gitster/git (which has more heads than the regular git.git), I get: $ wc v[02]* | head -n -1 2441 17098 340884 v0 733 5828 130263 v2 22 141 2037 v2-notags -Peff
