83fcadd636
Add a missing "a" before "bunch". Signed-off-by: Martin Ågren <martin.agren@gmail.com> Acked-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
225 lines
9.5 KiB
Plaintext
225 lines
9.5 KiB
Plaintext
git-maintenance(1)
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==================
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NAME
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----
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git-maintenance - Run tasks to optimize Git repository data
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SYNOPSIS
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--------
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[verse]
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'git maintenance' run [<options>]
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DESCRIPTION
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-----------
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Run tasks to optimize Git repository data, speeding up other Git commands
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and reducing storage requirements for the repository.
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Git commands that add repository data, such as `git add` or `git fetch`,
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are optimized for a responsive user experience. These commands do not take
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time to optimize the Git data, since such optimizations scale with the full
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size of the repository while these user commands each perform a relatively
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small action.
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The `git maintenance` command provides flexibility for how to optimize the
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Git repository.
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SUBCOMMANDS
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-----------
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register::
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Initialize Git config values so any scheduled maintenance will
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start running on this repository. This adds the repository to the
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`maintenance.repo` config variable in the current user's global
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config and enables some recommended configuration values for
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`maintenance.<task>.schedule`. The tasks that are enabled are safe
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for running in the background without disrupting foreground
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processes.
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+
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The `register` subcomand will also set the `maintenance.strategy` config
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value to `incremental`, if this value is not previously set. The
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`incremental` strategy uses the following schedule for each maintenance
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task:
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+
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--
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* `gc`: disabled.
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* `commit-graph`: hourly.
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* `prefetch`: hourly.
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* `loose-objects`: daily.
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* `incremental-repack`: daily.
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--
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+
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`git maintenance register` will also disable foreground maintenance by
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setting `maintenance.auto = false` in the current repository. This config
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setting will remain after a `git maintenance unregister` command.
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run::
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Run one or more maintenance tasks. If one or more `--task` options
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are specified, then those tasks are run in that order. Otherwise,
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the tasks are determined by which `maintenance.<task>.enabled`
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config options are true. By default, only `maintenance.gc.enabled`
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is true.
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start::
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Start running maintenance on the current repository. This performs
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the same config updates as the `register` subcommand, then updates
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the background scheduler to run `git maintenance run --scheduled`
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on an hourly basis.
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stop::
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Halt the background maintenance schedule. The current repository
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is not removed from the list of maintained repositories, in case
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the background maintenance is restarted later.
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unregister::
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Remove the current repository from background maintenance. This
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only removes the repository from the configured list. It does not
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stop the background maintenance processes from running.
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TASKS
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-----
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commit-graph::
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The `commit-graph` job updates the `commit-graph` files incrementally,
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then verifies that the written data is correct. The incremental
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write is safe to run alongside concurrent Git processes since it
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will not expire `.graph` files that were in the previous
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`commit-graph-chain` file. They will be deleted by a later run based
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on the expiration delay.
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prefetch::
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The `prefetch` task updates the object directory with the latest
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objects from all registered remotes. For each remote, a `git fetch`
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command is run. The refmap is custom to avoid updating local or remote
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branches (those in `refs/heads` or `refs/remotes`). Instead, the
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remote refs are stored in `refs/prefetch/<remote>/`. Also, tags are
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not updated.
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+
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This is done to avoid disrupting the remote-tracking branches. The end users
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expect these refs to stay unmoved unless they initiate a fetch. With prefetch
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task, however, the objects necessary to complete a later real fetch would
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already be obtained, so the real fetch would go faster. In the ideal case,
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it will just become an update to a bunch of remote-tracking branches without
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any object transfer.
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gc::
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Clean up unnecessary files and optimize the local repository. "GC"
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stands for "garbage collection," but this task performs many
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smaller tasks. This task can be expensive for large repositories,
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as it repacks all Git objects into a single pack-file. It can also
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be disruptive in some situations, as it deletes stale data. See
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linkgit:git-gc[1] for more details on garbage collection in Git.
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loose-objects::
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The `loose-objects` job cleans up loose objects and places them into
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pack-files. In order to prevent race conditions with concurrent Git
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commands, it follows a two-step process. First, it deletes any loose
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objects that already exist in a pack-file; concurrent Git processes
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will examine the pack-file for the object data instead of the loose
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object. Second, it creates a new pack-file (starting with "loose-")
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containing a batch of loose objects. The batch size is limited to 50
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thousand objects to prevent the job from taking too long on a
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repository with many loose objects. The `gc` task writes unreachable
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objects as loose objects to be cleaned up by a later step only if
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they are not re-added to a pack-file; for this reason it is not
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advisable to enable both the `loose-objects` and `gc` tasks at the
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same time.
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incremental-repack::
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The `incremental-repack` job repacks the object directory
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using the `multi-pack-index` feature. In order to prevent race
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conditions with concurrent Git commands, it follows a two-step
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process. First, it calls `git multi-pack-index expire` to delete
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pack-files unreferenced by the `multi-pack-index` file. Second, it
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calls `git multi-pack-index repack` to select several small
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pack-files and repack them into a bigger one, and then update the
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`multi-pack-index` entries that refer to the small pack-files to
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refer to the new pack-file. This prepares those small pack-files
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for deletion upon the next run of `git multi-pack-index expire`.
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The selection of the small pack-files is such that the expected
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size of the big pack-file is at least the batch size; see the
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`--batch-size` option for the `repack` subcommand in
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linkgit:git-multi-pack-index[1]. The default batch-size is zero,
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which is a special case that attempts to repack all pack-files
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into a single pack-file.
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OPTIONS
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-------
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--auto::
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When combined with the `run` subcommand, run maintenance tasks
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only if certain thresholds are met. For example, the `gc` task
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runs when the number of loose objects exceeds the number stored
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in the `gc.auto` config setting, or when the number of pack-files
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exceeds the `gc.autoPackLimit` config setting. Not compatible with
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the `--schedule` option.
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--schedule::
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When combined with the `run` subcommand, run maintenance tasks
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only if certain time conditions are met, as specified by the
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`maintenance.<task>.schedule` config value for each `<task>`.
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This config value specifies a number of seconds since the last
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time that task ran, according to the `maintenance.<task>.lastRun`
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config value. The tasks that are tested are those provided by
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the `--task=<task>` option(s) or those with
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`maintenance.<task>.enabled` set to true.
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--quiet::
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Do not report progress or other information over `stderr`.
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--task=<task>::
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If this option is specified one or more times, then only run the
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specified tasks in the specified order. If no `--task=<task>`
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arguments are specified, then only the tasks with
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`maintenance.<task>.enabled` configured as `true` are considered.
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See the 'TASKS' section for the list of accepted `<task>` values.
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TROUBLESHOOTING
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---------------
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The `git maintenance` command is designed to simplify the repository
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maintenance patterns while minimizing user wait time during Git commands.
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A variety of configuration options are available to allow customizing this
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process. The default maintenance options focus on operations that complete
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quickly, even on large repositories.
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Users may find some cases where scheduled maintenance tasks do not run as
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frequently as intended. Each `git maintenance run` command takes a lock on
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the repository's object database, and this prevents other concurrent
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`git maintenance run` commands from running on the same repository. Without
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this safeguard, competing processes could leave the repository in an
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unpredictable state.
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The background maintenance schedule runs `git maintenance run` processes
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on an hourly basis. Each run executes the "hourly" tasks. At midnight,
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that process also executes the "daily" tasks. At midnight on the first day
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of the week, that process also executes the "weekly" tasks. A single
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process iterates over each registered repository, performing the scheduled
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tasks for that frequency. Depending on the number of registered
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repositories and their sizes, this process may take longer than an hour.
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In this case, multiple `git maintenance run` commands may run on the same
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repository at the same time, colliding on the object database lock. This
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results in one of the two tasks not running.
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If you find that some maintenance windows are taking longer than one hour
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to complete, then consider reducing the complexity of your maintenance
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tasks. For example, the `gc` task is much slower than the
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`incremental-repack` task. However, this comes at a cost of a slightly
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larger object database. Consider moving more expensive tasks to be run
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less frequently.
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Expert users may consider scheduling their own maintenance tasks using a
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different schedule than is available through `git maintenance start` and
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Git configuration options. These users should be aware of the object
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database lock and how concurrent `git maintenance run` commands behave.
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Further, the `git gc` command should not be combined with
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`git maintenance run` commands. `git gc` modifies the object database
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but does not take the lock in the same way as `git maintenance run`. If
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possible, use `git maintenance run --task=gc` instead of `git gc`.
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GIT
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---
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Part of the linkgit:git[1] suite
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