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Diffstat (limited to 'Documentation/git-maintenance.txt')
| -rw-r--r-- | Documentation/git-maintenance.txt | 185 |
1 files changed, 181 insertions, 4 deletions
diff --git a/Documentation/git-maintenance.txt b/Documentation/git-maintenance.txt index 6fe1e5e105..e2cfb68ab5 100644 --- a/Documentation/git-maintenance.txt +++ b/Documentation/git-maintenance.txt @@ -92,10 +92,8 @@ commit-graph:: prefetch:: 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 refmap is custom to avoid updating local or remote - branches (those in `refs/heads` or `refs/remotes`). Instead, the - remote refs are stored in `refs/prefetch/<remote>/`. Also, tags are - not updated. + 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 @@ -145,6 +143,12 @@ incremental-repack:: which is a special case that attempts to repack all pack-files into a single pack-file. +pack-refs:: + 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 linkgit:git-pack-refs[1] + for more information. + OPTIONS ------- --auto:: @@ -175,6 +179,17 @@ OPTIONS `maintenance.<task>.enabled` configured as `true` are considered. See the 'TASKS' section for the list of accepted `<task>` values. +--scheduler=auto|crontab|systemd-timer|launchctl|schtasks:: + 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 `auto`. + TROUBLESHOOTING --------------- @@ -218,6 +233,168 @@ Further, the `git gc` command should not be combined with 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. + +BACKGROUND MAINTENANCE ON POSIX SYSTEMS +--------------------------------------- + +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: + +----------------------------------------------------------------------- +# BEGIN GIT MAINTENANCE SCHEDULE +# 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 + +# END GIT MAINTENANCE SCHEDULE +----------------------------------------------------------------------- + +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. + + +BACKGROUND MAINTENANCE ON LINUX SYSTEMD SYSTEMS +----------------------------------------------- + +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 it. + +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: + +----------------------------------------------------------------------- +~/.config/systemd/user/git-maintenance@.timer +~/.config/systemd/user/git-maintenance@.service +~/.config/systemd/user/timers.target.wants/git-maintenance@hourly.timer +~/.config/systemd/user/timers.target.wants/git-maintenance@daily.timer +~/.config/systemd/user/timers.target.wants/git-maintenance@weekly.timer +----------------------------------------------------------------------- + +`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 files. + +For more details, see `systemd.timer(5)`. + + +BACKGROUND MAINTENANCE ON MACOS SYSTEMS +--------------------------------------- + +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 command: + +----------------------------------------------------------------------- +$ ls ~/Library/LaunchAgents/org.git-scm.git* +org.git-scm.git.daily.plist +org.git-scm.git.hourly.plist +org.git-scm.git.weekly.plist +----------------------------------------------------------------------- + +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. + + +BACKGROUND MAINTENANCE ON WINDOWS SYSTEMS +----------------------------------------- + +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. + GIT --- |