Speedy Git

I was hanging out in the #emacs IRC channel on Libera and there was some chat about using git repository mirrors because GNU's Savannah servers are over-loaded due to AI scrapers and the like. I mentioned that I have git set up to do a first pull from Github, because I don't mind wasting Microsoft's bandwidth, then "topping up" from Savannah and Corwin Brust asked about it, so here's a wee write up.

I'm going to create a brand new clone of the Emacs repo on my machine, but it's simple enough to do this on an existing repo.

  mkdir emacs
  cd emacs
  git init .

Add Savannah as "origin".

  git remote add origin https://git.savannah.gnu.org/git/emacs.git

Doing a git fetch at this stage took so long I got bored waiting.

Now add a faster mirror. This may not always be up-to-date, so be aware of that.

  git remote add gh https://github.com/emacs-mirror/emacs.git

And now you can git fetch gh for a quick¹ update.

At this point git fetch --all will fetch from both Github and Savannah, but it appears to do it in the order they're configured. We want to pull from Github first to take some load off Savannah, so we create a group, defined in the order we want.

  # Create a group called "all"
  git config remotes.all "gh origin"

And now git fetch all, not --all, will use the members of the group in the order we defined, so we download the bulk of the updates from Github, then grab any remaining from Savannah. There's a decent chance it won't actually download anything from Savannah, but you know you're up-to-date anyway!

  git remote add sh https://git.sr.ht/~emacs/emacs
  git config remotes.fast "gh sh"

  git fetch --multiple -j 0 fast

  git config remotes.all "fast origin"