Runs a number of housekeeping tasks within the current repository,
such as compressing file revisions (to reduce disk space and increase
performance) and removing unreachable objects which may have been
created from prior invocations of git add.
Users are encouraged to run this task on a regular basis within each
repository to maintain good disk space utilization and good operating
Some git commands may automatically run git gc; see the --auto flag
below for details. If you know what you’re doing and all you want is
to disable this behavior permanently without further considerations,
$ git config --global gc.auto 0
Usually git gc runs very quickly while providing good disk space
utilization and performance. This option will cause git gc to
more aggressively optimize the repository at the expense of
taking much more time. The effects of this optimization are
persistent, so this option only needs to be used occasionally;
every few hundred changesets or so.
With this option, git gc checks whether any housekeeping is
required; if not, it exits without performing any work. Some git
commands run git gc --auto after performing operations that could
create many loose objects.
Housekeeping is required if there are too many loose objects or
too many packs in the repository. If the number of loose objects
exceeds the value of the gc.auto configuration variable, then all
loose objects are combined into a single pack using git repack -d-l. Setting the value of gc.auto to 0 disables automatic packing
of loose objects.
If the number of packs exceeds the value of gc.autoPackLimit,
then existing packs (except those marked with a .keep file) are
consolidated into a single pack by using the -A option of gitrepack. Setting gc.autoPackLimit to 0 disables automatic
consolidation of packs.
Prune loose objects older than date (default is 2 weeks ago,
overridable by the config variable gc.pruneExpire). --prune=all
prunes loose objects regardless of their age and increases the
risk of corruption if another process is writing to the
repository concurrently; see "NOTES" below. --prune is on by
Do not prune any loose objects.
Suppress all progress reports.
Force git gc to run even if there may be another git gc instance
running on this repository.
The optional configuration variable gc.reflogExpire can be set to
indicate how long historical entries within each branch’s reflog
should remain available in this repository. The setting is expressed
as a length of time, for example 90 days or 3 months. It defaults to
The optional configuration variable gc.reflogExpireUnreachable can be
set to indicate how long historical reflog entries which are not part
of the current branch should remain available in this repository.
These types of entries are generally created as a result of using gitcommit --amend or git rebase and are the commits prior to the amend
or rebase occurring. Since these changes are not part of the current
project most users will want to expire them sooner. This option
defaults to 30 days.
The above two configuration variables can be given to a pattern. For
example, this sets non-default expiry values only to remote-tracking
reflogExpire = never
reflogExpireUnreachable = 3 days
The optional configuration variable gc.rerereResolved indicates how
long records of conflicted merge you resolved earlier are kept. This
defaults to 60 days.
The optional configuration variable gc.rerereUnresolved indicates how
long records of conflicted merge you have not resolved are kept. This
defaults to 15 days.
The optional configuration variable gc.packRefs determines if git gc
runs git pack-refs. This can be set to "notbare" to enable it within
all non-bare repos or it can be set to a boolean value. This defaults
The optional configuration variable ‘gc.aggressiveWindow` controls
how much time is spent optimizing the delta compression of the
objects in the repository when the --aggressive option is specified.
The larger the value, the more time is spent optimizing the delta
compression. See the documentation for the --window’ option in
git-repack(1) for more details. This defaults to 250.
Similarly, the optional configuration variable gc.aggressiveDepth
controls --depth option in git-repack(1). This defaults to 50.
The optional configuration variable gc.pruneExpire controls how old
the unreferenced loose objects have to be before they are pruned. The
default is "2 weeks ago".
git gc tries very hard not to delete objects that are referenced
anywhere in your repository. In particular, it will keep not only
objects referenced by your current set of branches and tags, but also
objects referenced by the index, remote-tracking branches, refs saved
by git filter-branch in refs/original/, or reflogs (which may
reference commits in branches that were later amended or rewound). If
you are expecting some objects to be deleted and they aren’t, check
all of those locations and decide whether it makes sense in your case
to remove those references.
On the other hand, when git gc runs concurrently with another
process, there is a risk of it deleting an object that the other
process is using but hasn’t created a reference to. This may just
cause the other process to fail or may corrupt the repository if the
other process later adds a reference to the deleted object. Git has
two features that significantly mitigate this problem:
1. Any object with modification time newer than the --prune date is
kept, along with everything reachable from it.
2. Most operations that add an object to the database update the
modification time of the object if it is already present so that
However, these features fall short of a complete solution, so users
who run commands concurrently have to live with some risk of
corruption (which seems to be low in practice) unless they turn off
automatic garbage collection with git config gc.auto 0.
This page is part of the git (Git distributed version control system)
project. Information about the project can be found at
⟨http://git-scm.com/⟩. If you have a bug report for this manual page,
see ⟨http://git-scm.com/community⟩. This page was obtained from the
project's upstream Git repository ⟨https://github.com/git/git.git⟩ on
2017-03-13. If you discover any rendering problems in this HTML ver‐
sion of the page, or you believe there is a better or more up-to-date
source for the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original man‐
ual page), send a mail to email@example.com
Git 184.108.40.206.g625568 03/12/2017 GIT-GC(1)