Dangling objects are commits, blobs, or trees that are no longer referenced by any branch, tag, or the reflog. They exist in Git's object database but aren't part of any reachable history.
commit A -- commit B -- commit C (HEAD)
\
commit B' (dangling after amending B)
Git creates dangling objects during normal operations when commits or blobs become unreferenced. Common scenarios include:
- Unstaging files: When you run
git restore --staged my_file, the file staged usinggit add my_filebecomes dangling - Amending commits: When you run
git commit --amend, the original commit becomes dangling - Rebasing: Old commits are replaced with new ones, leaving the originals dangling
- Resetting branches:
git reset --hardmoves HEAD, leaving previous commits dangling - Deleting branches: Commits unique to deleted branches become dangling
- Failed merges or rebases: Temporary objects created during these operations may be left behind
Git doesn't immediately delete dangling objects. Instead, it has built-in garbage collection (GC) that runs automatically:
- Trigger: Runs when the repository has too many loose objects (usually after ~6,700 objects)
- Grace period: Unreachable objects are kept for a default period:
- Recent dangling objects (< 2 weeks old): Kept in case you need to recover them
- Old dangling objects (> 2 weeks old): Eligible for deletion during GC
- Reflog protection: Objects referenced in the reflog are kept until the reflog entry expires (default: 90 days)
# Amend a commit from 3 weeks ago
git commit --amend
# The original commit is now dangling and > 2 weeks old
# Next automatic GC will remove it# Create and amend a commit today
git commit -m "Initial commit"
git commit --amend -m "Amended commit"
# The original commit is dangling but:
# - Less than 2 weeks old (grace period)
# - Still in reflog (90-day default retention)
# Git will NOT garbage collect this yetYou can view dangling objects with:
git fsck --unreachable --no-reflogsTo immediately remove ALL dangling objects (including recent ones and those in reflog):
# Step 1: Expire all reflog entries immediately
git reflog expire --expire-unreachable=now --all
# Step 2: Run garbage collection with immediate pruning
git gc --prune=now-
git reflog expire --expire-unreachable=now --all- Expires all unreachable reflog entries immediately
--expire-unreachable=now: Don't wait for the grace period--all: Apply to all refs, not just the current branch
-
git gc --prune=now- Runs garbage collection
--prune=now: Delete all loose objects that are unreachable NOW (instead of waiting for the default grace period)
Caution
This operation is permanent and irreversible.
- Lost recovery options: You cannot recover accidentally deleted commits, amended commits, or reset branches
- Reflog history cleared: Your safety net for undoing mistakes is removed
- Collaborator issues: If others have references to commits you've pruned, they may encounter errors
- No undo: There is no way to restore garbage-collected objects
✅ Safe scenarios:
- Cleaning up after large rebases in a personal repository
- Removing sensitive data that was accidentally committed
- Reducing repository size after confirmed unwanted history removal
❌ Avoid when:
- You're unsure about recent Git operations
- Working in a shared/collaborative repository
- You might need to recover recent changes
- You haven't backed up important work
To see what would be removed without actually deleting:
# View unreachable objects
git fsck --unreachable --no-reflogs
# See reflog entries
git reflog show --all
# Estimate size savings
git count-objects -v