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Benchmark results of the fastest way to check if a git branch is dirty

Tested against the WebKit git repo by entering the repo with 1 file dirty.


git diff --quiet --ignore-submodules HEAD # Will tell if there are any uncomitted changes, staged or not.
0.6 sec

git diff-index --quiet HEAD # Only tracked
2 sec

git diff --shortstat
8.2 sec

git status --porcelain
42 sec

zstyle ':vcs_info:*' check-for-changes true
50 sec

@artjock
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artjock commented Feb 3, 2014

Did you try git status -suno? It's working faster for me and have the same limitations.
Full version is here: https://github.com/artjock/dotfiles/blob/master/bash/config#L20

@ericbn
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ericbn commented Oct 14, 2016

Unless you want to take untracked files into account too. The best I've come up with is:

git diff-files --no-ext-diff --quiet || git diff-index --no-ext-diff --quiet --cached HEAD

This is the benchmark I got in a NFS filesystem with the WebKit repo clean:

Command Real time (secs)
git ls-files --other --exclude-standard (lists untracked files) 2.756
git status --porcelain (lists indexed, unindexed and untracked files) 2.313
git diff-index --no-ext-diff --quiet --cached HEAD (checks indexed files) 0.317
git diff-files --no-ext-diff --quiet (checks unindexed files) 0.022

@nh2
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nh2 commented Dec 24, 2020

git diff-index --quiet HEAD -- can return outdated information unless you run git update-index -q --refresh (or a non-plumbing git status) first, (see https://stackoverflow.com/questions/2657935/checking-for-a-dirty-index-or-untracked-files-with-git/2659808#comment28747279_2659808) so it's not a fair comparison vs git status --porcelain without that.

Also any use of git diff-index --no-ext-diff --quiet --cached HEAD breaks if there's a file called HEAD in the repo; you need to use git diff-index --no-ext-diff --quiet --cached HEAD --, see here.

Finally, I found plumbing commands to be slower than the porcelain commands when the goal is to ignore untracked files in a repo with many large untracked files (not WebKit in this case) with git 2.29.2:

  • time (git diff-files --quiet --no-ext-diff || (git update-index -q --refresh; git diff-index --quiet --no-ext-diff --cached HEAD --))
    • 255 ms mean
  • time git status --porcelain --untracked-files=no > /dev/null
    • 110 ms mean

This was also observed here.

Do there exist any plumbing commands that are as fast and as correct as the porcelain commands? (Also asked here.)

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