What does "Auto packing the repository for optimum performance" mean?

git git-rebase git-push
Furqan Asghar picture Furqan Asghar · Dec 26, 2011 · Viewed 67.6k times · Source

I'm having a problem with my git repo. For the last couple of days whenever I do a push to the server I get this message: "Auto packing the repository for optimum performance", and it does not seem to go away and return the shell.

I also tried checking out to a new branch and then doing a rebase on my previous branch and then did git gc to remove the unused history objects and then did a push but still this message appears. Please let me know what's going on with my repo.

Answer

Cascabel picture Cascabel · Dec 26, 2011

Short version: it means what it says, and if you just let it finish, all will be well.

During most operations which can potentially increase the number of loose (unpacked) objects in the repository (including pushes), Git invokes git gc --auto. If there are enough loose objects (by default, at least 6700), it will then invoke git repack -d -l to pack them. If there are too many separate packs, it will also repack them into one.

A pack is a delta-compressed single file, containing a large number of objects. It's more efficient to store objects in packs, but it takes time to pack (compress) objects, so Git initially creates loose objects, then packs them in batches now and then, via automatic invocation of git gc --auto.

If you let Git finish repacking, this won't happen again for a while. It can indeed take a while, especially if you have a lot of large binary objects, but if it's triggering, then it's a sign that it will probably drastically reduce the amount of disk space taken by the repo. If you really don't want it to happen, you can change the config parameter gc.auto. If you increase it to something much larger than 6700, it will happen less frequently, but take longer when it does. If you decrease it, it'll still have to do your current repack, but subsequently it will happen more often and finish more quickly. If you set it to 0, it will disable automatic repacking.

See man git-gc (under --auto) and man git-config (under gc.auto) for more information.

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