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       git-maintenance - Run tasks to optimize Git repository data


       git maintenance run [<options>]
       git maintenance start [--scheduler=<scheduler>]
       git maintenance (stop|register|unregister)


       Run tasks to optimize Git repository data, speeding up other Git commands and reducing
       storage requirements for the repository.

       Git commands that add repository data, such as git add or git fetch, are optimized for a
       responsive user experience. These commands do not take time to optimize the Git data,
       since such optimizations scale with the full size of the repository while these user
       commands each perform a relatively small action.

       The git maintenance command provides flexibility for how to optimize the Git repository.


           Run one or more maintenance tasks. If one or more --task options are specified, then
           those tasks are run in that order. Otherwise, the tasks are determined by which
           maintenance.<task>.enabled config options are true. By default, only
           maintenance.gc.enabled is true.

           Start running maintenance on the current repository. This performs the same config
           updates as the register subcommand, then updates the background scheduler to run git
           maintenance run --scheduled on an hourly basis.

           Halt the background maintenance schedule. The current repository is not removed from
           the list of maintained repositories, in case the background maintenance is restarted

           Initialize Git config values so any scheduled maintenance will start running on this
           repository. This adds the repository to the maintenance.repo config variable in the
           current user’s global config and enables some recommended configuration values for
           maintenance.<task>.schedule. The tasks that are enabled are safe for running in the
           background without disrupting foreground processes.

           The register subcommand will also set the maintenance.strategy config value to
           incremental, if this value is not previously set. The incremental strategy uses the
           following schedule for each maintenance task:

           •   gc: disabled.

           •   commit-graph: hourly.

           •   prefetch: hourly.

           •   loose-objects: daily.

           •   incremental-repack: daily.

           git maintenance register will also disable foreground maintenance by setting
  = false in the current repository. This config setting will remain
           after a git maintenance unregister command.

           Remove the current repository from background maintenance. This only removes the
           repository from the configured list. It does not stop the background maintenance
           processes from running.


           The commit-graph job updates the commit-graph files incrementally, then verifies that
           the written data is correct. The incremental write is safe to run alongside concurrent
           Git processes since it will not expire .graph files that were in the previous
           commit-graph-chain file. They will be deleted by a later run based on the expiration

           The prefetch task updates the object directory with the latest objects from all
           registered remotes. For each remote, a git fetch command is run. The configured
           refspec is modified to place all requested refs within refs/prefetch/. Also, tags are
           not updated.

           This is done to avoid disrupting the remote-tracking branches. The end users expect
           these refs to stay unmoved unless they initiate a fetch. With prefetch task, however,
           the objects necessary to complete a later real fetch would already be obtained, so the
           real fetch would go faster. In the ideal case, it will just become an update to a
           bunch of remote-tracking branches without any object transfer.

           Clean up unnecessary files and optimize the local repository. "GC" stands for "garbage
           collection," but this task performs many smaller tasks. This task can be expensive for
           large repositories, as it repacks all Git objects into a single pack-file. It can also
           be disruptive in some situations, as it deletes stale data. See git-gc(1) for more
           details on garbage collection in Git.

           The loose-objects job cleans up loose objects and places them into pack-files. In
           order to prevent race conditions with concurrent Git commands, it follows a two-step
           process. First, it deletes any loose objects that already exist in a pack-file;
           concurrent Git processes will examine the pack-file for the object data instead of the
           loose object. Second, it creates a new pack-file (starting with "loose-") containing a
           batch of loose objects. The batch size is limited to 50 thousand objects to prevent
           the job from taking too long on a repository with many loose objects. The gc task
           writes unreachable objects as loose objects to be cleaned up by a later step only if
           they are not re-added to a pack-file; for this reason it is not advisable to enable
           both the loose-objects and gc tasks at the same time.

           The incremental-repack job repacks the object directory using the multi-pack-index
           feature. In order to prevent race conditions with concurrent Git commands, it follows
           a two-step process. First, it calls git multi-pack-index expire to delete pack-files
           unreferenced by the multi-pack-index file. Second, it calls git multi-pack-index
           repack to select several small pack-files and repack them into a bigger one, and then
           update the multi-pack-index entries that refer to the small pack-files to refer to the
           new pack-file. This prepares those small pack-files for deletion upon the next run of
           git multi-pack-index expire. The selection of the small pack-files is such that the
           expected size of the big pack-file is at least the batch size; see the --batch-size
           option for the repack subcommand in git-multi-pack-index(1). The default batch-size is
           zero, which is a special case that attempts to repack all pack-files into a single

           The pack-refs task collects the loose reference files and collects them into a single
           file. This speeds up operations that need to iterate across many references. See git-
           pack-refs(1) for more information.


           When combined with the run subcommand, run maintenance tasks only if certain
           thresholds are met. For example, the gc task runs when the number of loose objects
           exceeds the number stored in the config setting, or when the number of
           pack-files exceeds the gc.autoPackLimit config setting. Not compatible with the
           --schedule option.

           When combined with the run subcommand, run maintenance tasks only if certain time
           conditions are met, as specified by the maintenance.<task>.schedule config value for
           each <task>. This config value specifies a number of seconds since the last time that
           task ran, according to the maintenance.<task>.lastRun config value. The tasks that are
           tested are those provided by the --task=<task> option(s) or those with
           maintenance.<task>.enabled set to true.

           Do not report progress or other information over stderr.

           If this option is specified one or more times, then only run the specified tasks in
           the specified order. If no --task=<task> arguments are specified, then only the tasks
           with maintenance.<task>.enabled configured as true are considered. See the TASKS
           section for the list of accepted <task> values.

           When combined with the start subcommand, specify the scheduler for running the hourly,
           daily and weekly executions of git maintenance run. Possible values for <scheduler>
           are auto, crontab (POSIX), systemd-timer (Linux), launchctl (macOS), and schtasks
           (Windows). When auto is specified, the appropriate platform-specific scheduler is
           used; on Linux, systemd-timer is used if available, otherwise crontab. Default is


       The git maintenance command is designed to simplify the repository maintenance patterns
       while minimizing user wait time during Git commands. A variety of configuration options
       are available to allow customizing this process. The default maintenance options focus on
       operations that complete quickly, even on large repositories.

       Users may find some cases where scheduled maintenance tasks do not run as frequently as
       intended. Each git maintenance run command takes a lock on the repository’s object
       database, and this prevents other concurrent git maintenance run commands from running on
       the same repository. Without this safeguard, competing processes could leave the
       repository in an unpredictable state.

       The background maintenance schedule runs git maintenance run processes on an hourly basis.
       Each run executes the "hourly" tasks. At midnight, that process also executes the "daily"
       tasks. At midnight on the first day of the week, that process also executes the "weekly"
       tasks. A single process iterates over each registered repository, performing the scheduled
       tasks for that frequency. Depending on the number of registered repositories and their
       sizes, this process may take longer than an hour. In this case, multiple git maintenance
       run commands may run on the same repository at the same time, colliding on the object
       database lock. This results in one of the two tasks not running.

       If you find that some maintenance windows are taking longer than one hour to complete,
       then consider reducing the complexity of your maintenance tasks. For example, the gc task
       is much slower than the incremental-repack task. However, this comes at a cost of a
       slightly larger object database. Consider moving more expensive tasks to be run less

       Expert users may consider scheduling their own maintenance tasks using a different
       schedule than is available through git maintenance start and Git configuration options.
       These users should be aware of the object database lock and how concurrent git maintenance
       run commands behave. Further, the git gc command should not be combined with git
       maintenance run commands. git gc modifies the object database but does not take the lock
       in the same way as git maintenance run. If possible, use git maintenance run --task=gc
       instead of git gc.

       The following sections describe the mechanisms put in place to run background maintenance
       by git maintenance start and how to customize them.


       The standard mechanism for scheduling background tasks on POSIX systems is cron(8). This
       tool executes commands based on a given schedule. The current list of user-scheduled tasks
       can be found by running crontab -l. The schedule written by git maintenance start is
       similar to this:

           # The following schedule was created by Git
           # Any edits made in this region might be
           # replaced in the future by a Git command.

           0 1-23 * * * "/<path>/git" --exec-path="/<path>" for-each-repo --config=maintenance.repo maintenance run --schedule=hourly
           0 0 * * 1-6 "/<path>/git" --exec-path="/<path>" for-each-repo --config=maintenance.repo maintenance run --schedule=daily
           0 0 * * 0 "/<path>/git" --exec-path="/<path>" for-each-repo --config=maintenance.repo maintenance run --schedule=weekly


       The comments are used as a region to mark the schedule as written by Git. Any
       modifications within this region will be completely deleted by git maintenance stop or
       overwritten by git maintenance start.

       The crontab entry specifies the full path of the git executable to ensure that the
       executed git command is the same one with which git maintenance start was issued
       independent of PATH. If the same user runs git maintenance start with multiple Git
       executables, then only the latest executable is used.

       These commands use git for-each-repo --config=maintenance.repo to run git maintenance run
       --schedule=<frequency> on each repository listed in the multi-valued maintenance.repo
       config option. These are typically loaded from the user-specific global config. The git
       maintenance process then determines which maintenance tasks are configured to run on each
       repository with each <frequency> using the maintenance.<task>.schedule config options.
       These values are loaded from the global or repository config values.

       If the config values are insufficient to achieve your desired background maintenance
       schedule, then you can create your own schedule. If you run crontab -e, then an editor
       will load with your user-specific cron schedule. In that editor, you can add your own
       schedule lines. You could start by adapting the default schedule listed earlier, or you
       could read the crontab(5) documentation for advanced scheduling techniques. Please do use
       the full path and --exec-path techniques from the default schedule to ensure you are
       executing the correct binaries in your schedule.


       While Linux supports cron, depending on the distribution, cron may be an optional package
       not necessarily installed. On modern Linux distributions, systemd timers are superseding

       If user systemd timers are available, they will be used as a replacement of cron.

       In this case, git maintenance start will create user systemd timer units and start the
       timers. The current list of user-scheduled tasks can be found by running systemctl --user
       list-timers. The timers written by git maintenance start are similar to this:

           $ systemctl --user list-timers
           NEXT                         LEFT          LAST                         PASSED     UNIT                         ACTIVATES
           Thu 2021-04-29 19:00:00 CEST 42min left    Thu 2021-04-29 18:00:11 CEST 17min ago  git-maintenance@hourly.timer git-maintenance@hourly.service
           Fri 2021-04-30 00:00:00 CEST 5h 42min left Thu 2021-04-29 00:00:11 CEST 18h ago    git-maintenance@daily.timer  git-maintenance@daily.service
           Mon 2021-05-03 00:00:00 CEST 3 days left   Mon 2021-04-26 00:00:11 CEST 3 days ago git-maintenance@weekly.timer git-maintenance@weekly.service

       One timer is registered for each --schedule=<frequency> option.

       The definition of the systemd units can be inspected in the following files:


       git maintenance start will overwrite these files and start the timer again with systemctl
       --user, so any customization should be done by creating a drop-in file, i.e. a .conf
       suffixed file in the ~/.config/systemd/user/git-maintenance@.service.d directory.

       git maintenance stop will stop the user systemd timers and delete the above mentioned

       For more details, see systemd.timer(5).


       While macOS technically supports cron, using crontab -e requires elevated privileges and
       the executed process does not have a full user context. Without a full user context, Git
       and its credential helpers cannot access stored credentials, so some maintenance tasks are
       not functional.

       Instead, git maintenance start interacts with the launchctl tool, which is the recommended
       way to schedule timed jobs in macOS. Scheduling maintenance through git maintenance
       (start|stop) requires some launchctl features available only in macOS 10.11 or later.

       Your user-specific scheduled tasks are stored as XML-formatted .plist files in
       ~/Library/LaunchAgents/. You can see the currently-registered tasks using the following

           $ ls ~/Library/LaunchAgents/org.git-scm.git*

       One task is registered for each --schedule=<frequency> option. To inspect how the XML
       format describes each schedule, open one of these .plist files in an editor and inspect
       the <array> element following the <key>StartCalendarInterval</key> element.

       git maintenance start will overwrite these files and register the tasks again with
       launchctl, so any customizations should be done by creating your own .plist files with
       distinct names. Similarly, the git maintenance stop command will unregister the tasks with
       launchctl and delete the .plist files.

       To create more advanced customizations to your background tasks, see launchctl.plist(5)
       for more information.


       Windows does not support cron and instead has its own system for scheduling background
       tasks. The git maintenance start command uses the schtasks command to submit tasks to this
       system. You can inspect all background tasks using the Task Scheduler application. The
       tasks added by Git have names of the form Git Maintenance (<frequency>). The Task
       Scheduler GUI has ways to inspect these tasks, but you can also export the tasks to XML
       files and view the details there.

       Note that since Git is a console application, these background tasks create a console
       window visible to the current user. This can be changed manually by selecting the "Run
       whether user is logged in or not" option in Task Scheduler. This change requires a
       password input, which is why git maintenance start does not select it by default.

       If you want to customize the background tasks, please rename the tasks so future calls to
       git maintenance (start|stop) do not overwrite your custom tasks.


       Part of the git(1) suite