Stopping a git gc --aggressive, is that a bad thing?

Question

I am running a git gc --aggressive on a very large repo (apx 100 gb). It's been running since two nights ago, and as of a couple hours, it has been stuck on: "Compressing Objects: 99% (76496/76777)"

If I Ctrl-C the process, what are the consequences? Will my repo be unusable? My intuition says no, but I'd like some opinions. Thanks!

Answer 1

git is supposed to be always safe from interruptions like this. If you are worried, though, I suggest Ctrl+Z and then run a git fsck --full to make sure the system is consistent.

There are a number of git-config variables which might help your git-gc go faster. I use the following on one particular large repo, but there are many more options to randomly try (or carefully study, whichever).

git config pack.threads 1 git config pack.deltaCacheSize 1 git config core.packedGitWindowSize 16m git config core.packedGitLimit 128m git config pack.windowMemory 512m 

These only help if your problem is that you are running out of memory.

Answer 2

FWIW, I just corrupted a repository by aborting git gc with CTRL+C. git fsck now shows the following errors:

error: HEAD: invalid sha1 pointer [...] error: refs/heads/master does not point to a valid object! notice: No default references 

And quite a few

dangling commit [...] 

I'm not going to investigate on this, but I would like to point out that I'm going to avoid aborting git gc.