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authorJunio C Hamano <gitster@pobox.com>2020-11-18 21:32:53 (GMT)
committerJunio C Hamano <gitster@pobox.com>2020-11-18 21:32:53 (GMT)
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parentc042c455d4ffb9b5ed0c280301b5661f3efad572 (diff)
parent0016b618182f642771dc589cf0090289f9fe1b4f (diff)
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Merge branch 'ds/maintenance-part-3'
Parts of "git maintenance" to ease writing crontab entries (and other scheduling system configuration) for it. * ds/maintenance-part-3: maintenance: add troubleshooting guide to docs maintenance: use 'incremental' strategy by default maintenance: create maintenance.strategy config maintenance: add start/stop subcommands maintenance: add [un]register subcommands for-each-repo: run subcommands on configured repos maintenance: add --schedule option and config maintenance: optionally skip --auto process
Diffstat (limited to 'Documentation/git-maintenance.txt')
-rw-r--r--Documentation/git-maintenance.txt99
1 files changed, 98 insertions, 1 deletions
diff --git a/Documentation/git-maintenance.txt b/Documentation/git-maintenance.txt
index 3f5d894..6fec1eb 100644
--- a/Documentation/git-maintenance.txt
+++ b/Documentation/git-maintenance.txt
@@ -29,6 +29,32 @@ Git repository.
SUBCOMMANDS
-----------
+register::
+ 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` subcomand 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 `maintenance.auto = false` in the current repository. This config
+setting will remain after a `git maintenance unregister` command.
+
run::
Run one or more maintenance tasks. If one or more `--task` options
are specified, then those tasks are run in that order. Otherwise,
@@ -36,6 +62,22 @@ run::
config options are true. By default, only `maintenance.gc.enabled`
is true.
+start::
+ 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.
+
+stop::
+ Halt the background maintenance schedule. The current repository
+ is not removed from the list of maintained repositories, in case
+ the background maintenance is restarted later.
+
+unregister::
+ 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.
+
TASKS
-----
@@ -110,7 +152,18 @@ OPTIONS
only if certain thresholds are met. For example, the `gc` task
runs when the number of loose objects exceeds the number stored
in the `gc.auto` config setting, or when the number of pack-files
- exceeds the `gc.autoPackLimit` config setting.
+ exceeds the `gc.autoPackLimit` config setting. Not compatible with
+ the `--schedule` option.
+
+--schedule::
+ 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.
--quiet::
Do not report progress or other information over `stderr`.
@@ -122,6 +175,50 @@ OPTIONS
`maintenance.<task>.enabled` configured as `true` are considered.
See the 'TASKS' section for the list of accepted `<task>` values.
+
+TROUBLESHOOTING
+---------------
+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 frequently.
+
+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`.
+
+
GIT
---
Part of the linkgit:git[1] suite