Using Git Worktree
Often enough, you’re at the stage in your work where you’re running potentially time-consuming unit/integration tests. You have other work to do on that project, but you’re tied up waiting for the tests to finish (and hopefully pass).
I wanted to figure out an efficient way to work on new features while I’m testing another. You can’t switch the branch out from underneath the test, and making a copy/clone of the repository is an expensive operation (in disk space and/or network speed, especially with larger projects).
And I found git-worktree:
A git repository can support multiple working trees, allowing you to check out more than one branch at a time. […] a new working tree is associated with the repository, […] called a “linked working tree” as opposed to the “main working tree” prepared by “git init” or “git clone”. A repository has one main working tree[…] and zero or more linked working trees.
Here’s what it looks like in practice.
Create a new project
Create a new, empty project to work from (if you’re brave, skip this step and work against an existing repo):
mkdir -p ~/Demo/myproject cd ~/Demo/myproject git init . touch README.md git add README.md git commit -a -m "Initial response"
Create a Feature Branch and worktree
master branch should only contain code ready for general consumption. I use branches to work on new code, and merge when ready.
cd ~/Demo/myproject # Checkout the branch you want to base your new work on git checkout master # Create a new branch for this mythical new work git branch feature-24601 # Create a new worktree, in the Demo directory, for our new feature branch git worktree add ../myproject-24601 feature-24601 # Switch to the directory with the new worktree cd ../myproject-24601 # Confirm that we're in our new branch git status > On branch feature-24601
Now you’re free to hack on your new feature without stomping over your running tests.
# Write code, test, and documentation echo "Adding feature 24601." >> README.md git commit -a -m "Document new feature"
Merge feature branch
Switch back to master and merge your new feature.
cd ../myproject git merge feature-24601 Updating 873ef32..2da1c53 Fast-forward README.md | 1 + 1 file changed, 1 insertion(+)
When you’re done, clean up your repository. Future you will be happier.
# `prune` will remove worktrees pointing to directories that no longer exist rm -rf ../myproject-24601 git worktree prune # Delete the feature branch git branch -d feature-24601 > Deleted branch feature-24601 (was 2da1c53).
- Mixing worktree and submodules works but with the caveat that each worktree has a unique copy of submodules, rather than a hard link, so this will consume more disk space.
- You can’t create multiple worktrees for the same branch, but that’s generally not a problem if you’re following best git practices.
- Parallelize Development Using Git Worktrees, which I read to understand the basics of git-worktree.
- What goes wrong when using git worktree with git submodules
- Git Feature Branch Workflow