2010-10-22 10:47:19 +04:00
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#!/bin/sh
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test_description='basic git gc tests
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'
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. ./test-lib.sh
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2018-09-20 00:01:38 +03:00
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. "$TEST_DIRECTORY"/lib-terminal.sh
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2010-10-22 10:47:19 +04:00
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2018-04-15 18:36:17 +03:00
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test_expect_success 'setup' '
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# do not let the amount of physical memory affects gc
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# behavior, make sure we always pack everything to one pack by
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# default
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git config gc.bigPackThreshold 2g
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'
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2010-10-22 10:47:19 +04:00
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test_expect_success 'gc empty repository' '
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git gc
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'
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gc: remove gc.pid file at end of execution
This file isn't really harmful, but isn't useful either, and can create
minor annoyance for the user:
* It's confusing, as the presence of a *.pid file often implies that a
process is currently running. A user running "ls .git/" and finding
this file may incorrectly guess that a "git gc" is currently running.
* Leaving this file means that a "git gc" in an already gc-ed repo is
no-longer a no-op. A user running "git gc" in a set of repositories,
and then synchronizing this set (e.g. rsync -av, unison, ...) will see
all the gc.pid files as changed, which creates useless noise.
This patch unlinks the file after the garbage collection is done, so that
gc.pid is actually present only during execution.
Future versions of Git may want to use the information left in the gc.pid
file (e.g. for policies like "don't attempt to run a gc if one has
already been ran less than X hours ago"). If so, this patch can safely be
reverted. For now, let's not bother the users.
Explained-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Improved-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-10-17 03:11:46 +04:00
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test_expect_success 'gc does not leave behind pid file' '
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git gc &&
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test_path_is_missing .git/gc.pid
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'
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2010-10-22 10:47:19 +04:00
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test_expect_success 'gc --gobbledegook' '
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test_expect_code 129 git gc --nonsense 2>err &&
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2012-08-27 09:36:55 +04:00
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test_i18ngrep "[Uu]sage: git gc" err
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2010-10-22 10:47:19 +04:00
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'
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test_expect_success 'gc -h with invalid configuration' '
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mkdir broken &&
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(
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cd broken &&
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git init &&
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echo "[gc] pruneexpire = CORRUPT" >>.git/config &&
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test_expect_code 129 git gc -h >usage 2>&1
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) &&
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2012-08-27 09:36:55 +04:00
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test_i18ngrep "[Uu]sage" broken/usage
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2010-10-22 10:47:19 +04:00
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'
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2015-09-28 17:01:25 +03:00
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test_expect_success 'gc is not aborted due to a stale symref' '
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2015-09-28 17:01:13 +03:00
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git init remote &&
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(
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cd remote &&
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test_commit initial &&
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git clone . ../client &&
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git branch -m develop &&
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cd ../client &&
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git fetch --prune &&
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git gc
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)
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'
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2018-04-15 18:36:14 +03:00
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test_expect_success 'gc --keep-largest-pack' '
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test_create_repo keep-pack &&
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(
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cd keep-pack &&
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test_commit one &&
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test_commit two &&
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test_commit three &&
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git gc &&
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( cd .git/objects/pack && ls *.pack ) >pack-list &&
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test_line_count = 1 pack-list &&
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BASE_PACK=.git/objects/pack/pack-*.pack &&
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test_commit four &&
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git repack -d &&
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test_commit five &&
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git repack -d &&
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( cd .git/objects/pack && ls *.pack ) >pack-list &&
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test_line_count = 3 pack-list &&
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git gc --keep-largest-pack &&
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( cd .git/objects/pack && ls *.pack ) >pack-list &&
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test_line_count = 2 pack-list &&
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2019-05-23 20:27:23 +03:00
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awk "/^P /{print \$2}" <.git/objects/info/packs >pack-info &&
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test_line_count = 2 pack-info &&
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2018-04-15 18:36:14 +03:00
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test_path_is_file $BASE_PACK &&
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git fsck
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)
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'
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2016-12-29 01:45:41 +03:00
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test_expect_success 'auto gc with too many loose objects does not attempt to create bitmaps' '
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test_config gc.auto 3 &&
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test_config gc.autodetach false &&
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test_config pack.writebitmaps true &&
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# We need to create two object whose sha1s start with 17
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# since this is what git gc counts. As it happens, these
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# two blobs will do so.
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test_commit 263 &&
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test_commit 410 &&
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# Our first gc will create a pack; our second will create a second pack
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git gc --auto &&
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ls .git/objects/pack | sort >existing_packs &&
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test_commit 523 &&
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test_commit 790 &&
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git gc --auto 2>err &&
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test_i18ngrep ! "^warning:" err &&
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ls .git/objects/pack/ | sort >post_packs &&
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comm -1 -3 existing_packs post_packs >new &&
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comm -2 -3 existing_packs post_packs >del &&
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test_line_count = 0 del && # No packs are deleted
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test_line_count = 2 new # There is one new pack and its .idx
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'
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2018-09-20 00:01:38 +03:00
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test_expect_success 'gc --no-quiet' '
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git -c gc.writeCommitGraph=true gc --no-quiet >stdout 2>stderr &&
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test_must_be_empty stdout &&
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test_line_count = 1 stderr &&
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test_i18ngrep "Computing commit graph generation numbers" stderr
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'
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test_expect_success TTY 'with TTY: gc --no-quiet' '
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test_terminal git -c gc.writeCommitGraph=true gc --no-quiet >stdout 2>stderr &&
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test_must_be_empty stdout &&
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test_i18ngrep "Enumerating objects" stderr &&
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test_i18ngrep "Computing commit graph generation numbers" stderr
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'
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test_expect_success 'gc --quiet' '
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git -c gc.writeCommitGraph=true gc --quiet >stdout 2>stderr &&
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test_must_be_empty stdout &&
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test_must_be_empty stderr
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'
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gc: handle & check gc.reflogExpire config
Don't redundantly run "git reflog expire --all" when gc.reflogExpire
and gc.reflogExpireUnreachable are set to "never", and die immediately
if those configuration valuer are bad.
As an earlier "assert lack of early exit" change to the tests for "git
reflog expire" shows, an early check of gc.reflogExpire{Unreachable,}
isn't wanted in general for "git reflog expire", but it makes sense
for "gc" because:
1) Similarly to 8ab5aa4bd8 ("parseopt: handle malformed --expire
arguments more nicely", 2018-04-21) we'll now die early if the
config variables are set to invalid values.
We run "pack-refs" before "reflog expire", which can take a while,
only to then die on an invalid gc.reflogExpire{Unreachable,}
configuration.
2) Not invoking the command at all means it won't show up in trace
output, which makes what's going on more obvious when the two are
set to "never".
3) As a later change documents we lock the refs when looping over the
refs to expire, even in cases where we end up doing nothing due to
this config.
For the reasons noted in the earlier "assert lack of early exit"
change I don't think it's worth it to bend over backwards in "git
reflog expire" itself to carefully detect if we'll really do
nothing given the combination of all its possible options and skip
that locking, but that's easy to detect here in "gc" where we'll
only run "reflog expire" in a relatively simple mode.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-03-28 19:14:34 +03:00
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test_expect_success 'gc.reflogExpire{Unreachable,}=never skips "expire" via "gc"' '
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test_config gc.reflogExpire never &&
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test_config gc.reflogExpireUnreachable never &&
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GIT_TRACE=$(pwd)/trace.out git gc &&
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# Check that git-pack-refs is run as a sanity check (done via
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# gc_before_repack()) but that git-expire is not.
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grep -E "^trace: (built-in|exec|run_command): git pack-refs --" trace.out &&
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! grep -E "^trace: (built-in|exec|run_command): git reflog expire --" trace.out
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'
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test_expect_success 'one of gc.reflogExpire{Unreachable,}=never does not skip "expire" via "gc"' '
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>trace.out &&
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test_config gc.reflogExpire never &&
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GIT_TRACE=$(pwd)/trace.out git gc &&
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grep -E "^trace: (built-in|exec|run_command): git reflog expire --" trace.out
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'
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t6500: wait for detached auto gc at the end of the test script
The last test in 't6500-gc', 'background auto gc does not run if
gc.log is present and recent but does if it is old', added in
a831c06a2 (gc: ignore old gc.log files, 2017-02-10), may sporadically
trigger an error message from the test harness:
rm: cannot remove 'trash directory.t6500-gc/.git/objects': Directory not empty
The test in question ends with executing an auto gc in the backround,
which occasionally takes so long that it's still running when
'test_done' is about to remove the trash directory. This 'rm -rf
$trash' in the foreground might race with the detached auto gc to
create and delete files and directories, and gc might (re-)create a
path that 'rm' already visited and removed, triggering the above error
message when 'rm' attempts to remove its parent directory.
Commit bb05510e5 (t5510: run auto-gc in the foreground, 2016-05-01)
fixed the same problem in a different test script by simply
disallowing background gc. Unfortunately, what worked there is not
applicable here, because the purpose of this test is to check the
behavior of a detached auto gc.
Make sure that the test doesn't continue before the gc is finished in
the background with a clever bit of shell trickery:
- Open fd 9 in the shell, to be inherited by the background gc
process, because our daemonize() only closes the standard fds 0,
1 and 2.
- Duplicate this fd 9 to stdout.
- Read 'git gc's stdout, and thus fd 9, through a command
substitution. We don't actually care about gc's output, but this
construct has two useful properties:
- This read blocks until stdout or fd 9 are open. While stdout is
closed after the main gc process creates the background process
and exits, fd 9 remains open until the backround process exits.
- The variable assignment from the command substitution gets its
exit status from the command executed within the command
substitution, i.e. a failing main gc process will cause the test
to fail.
Note, that this fd trickery doesn't work on Windows, because due to
MSYS limitations the git process only inherits the standard fds 0, 1
and 2 from the shell. Luckily, it doesn't matter in this case,
because on Windows daemonize() is basically a noop, thus 'git gc
--auto' always runs in the foreground.
And since we can now continue the test reliably after the detached gc
finished, check that there is only a single packfile left at the end,
i.e. that the detached gc actually did what it was supposed to do.
Also add a comment at the end of the test script to warn developers of
future tests about this issue of long running detached gc processes.
Helped-by: Jeff King <peff@peff.net>
Helped-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-04-13 13:31:38 +03:00
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run_and_wait_for_auto_gc () {
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# We read stdout from gc for the side effect of waiting until the
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# background gc process exits, closing its fd 9. Furthermore, the
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# variable assignment from a command substitution preserves the
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# exit status of the main gc process.
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# Note: this fd trickery doesn't work on Windows, but there is no
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# need to, because on Win the auto gc always runs in the foreground.
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doesnt_matter=$(git gc --auto 9>&1)
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}
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gc: ignore old gc.log files
A server can end up in a state where there are lots of unreferenced
loose objects (say, because many users are doing a bunch of rebasing
and pushing their rebased branches). Running "git gc --auto" in
this state would cause a gc.log file to be created, preventing
future auto gcs, causing pack files to pile up. Since many git
operations are O(n) in the number of pack files, this would lead to
poor performance.
Git should never get itself into a state where it refuses to do any
maintenance, just because at some point some piece of the maintenance
didn't make progress.
Teach Git to ignore gc.log files which are older than (by default)
one day old, which can be tweaked via the gc.logExpiry configuration
variable. That way, these pack files will get cleaned up, if
necessary, at least once per day. And operators who find a need for
more-frequent gcs can adjust gc.logExpiry to meet their needs.
There is also some cleanup: a successful manual gc, or a
warning-free auto gc with an old log file, will remove any old
gc.log files.
It might still happen that manual intervention is required
(e.g. because the repo is corrupt), but at the very least it won't
be because Git is too dumb to try again.
Signed-off-by: David Turner <dturner@twosigma.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-02-11 00:28:22 +03:00
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test_expect_success 'background auto gc does not run if gc.log is present and recent but does if it is old' '
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test_commit foo &&
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test_commit bar &&
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git repack &&
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test_config gc.autopacklimit 1 &&
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test_config gc.autodetach true &&
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echo fleem >.git/gc.log &&
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gc: do not return error for prior errors in daemonized mode
Some build machines started consistently failing to fetch updated
source using "repo sync", with error
error: The last gc run reported the following. Please correct the root cause
and remove /build/.repo/projects/tools/git.git/gc.log.
Automatic cleanup will not be performed until the file is removed.
warning: There are too many unreachable loose objects; run 'git prune' to remove them.
The cause takes some time to describe.
In v2.0.0-rc0~145^2 (gc: config option for running --auto in
background, 2014-02-08), "git gc --auto" learned to run in the
background instead of blocking the invoking command. In this mode, it
closed stderr to avoid interleaving output with any subsequent
commands, causing warnings like the above to be swallowed; v2.6.3~24^2
(gc: save log from daemonized gc --auto and print it next time,
2015-09-19) addressed that by storing any diagnostic output in
.git/gc.log and allowing the next "git gc --auto" run to print it.
To avoid wasteful repeated fruitless gcs, when gc.log is present, the
subsequent "gc --auto" would die after printing its contents. Most
git commands, such as "git fetch", ignore the exit status from "git gc
--auto" so all is well at this point: the user gets to see the error
message, and the fetch succeeds, without a wasteful additional attempt
at an automatic gc.
External tools like repo[1], though, do care about the exit status
from "git gc --auto". In non-daemonized mode, the exit status is
straightforward: if there is an error, it is nonzero, but after a
warning like the above, the status is zero. The daemonized mode, as a
side effect of the other properties provided, offers a very strange
exit code convention:
- if no housekeeping was required, the exit status is 0
- the first real run, after forking into the background, returns exit
status 0 unconditionally. The parent process has no way to know
whether gc will succeed.
- if there is any diagnostic output in gc.log, subsequent runs return
a nonzero exit status to indicate that gc was not triggered.
There's nothing for the calling program to act on on the basis of that
error. Use status 0 consistently instead, to indicate that we decided
not to run a gc (just like if no housekeeping was required). This
way, repo and similar tools can get the benefit of the same behavior
as tools like "git fetch" that ignore the exit status from gc --auto.
Once the period of time described by gc.pruneExpire elapses, the
unreachable loose objects will be removed by "git gc --auto"
automatically.
[1] https://gerrit-review.googlesource.com/c/git-repo/+/10598/
Reported-by: Andrii Dehtiarov <adehtiarov@google.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-07-17 09:57:40 +03:00
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git gc --auto 2>err &&
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test_i18ngrep "^warning:" err &&
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gc: ignore old gc.log files
A server can end up in a state where there are lots of unreferenced
loose objects (say, because many users are doing a bunch of rebasing
and pushing their rebased branches). Running "git gc --auto" in
this state would cause a gc.log file to be created, preventing
future auto gcs, causing pack files to pile up. Since many git
operations are O(n) in the number of pack files, this would lead to
poor performance.
Git should never get itself into a state where it refuses to do any
maintenance, just because at some point some piece of the maintenance
didn't make progress.
Teach Git to ignore gc.log files which are older than (by default)
one day old, which can be tweaked via the gc.logExpiry configuration
variable. That way, these pack files will get cleaned up, if
necessary, at least once per day. And operators who find a need for
more-frequent gcs can adjust gc.logExpiry to meet their needs.
There is also some cleanup: a successful manual gc, or a
warning-free auto gc with an old log file, will remove any old
gc.log files.
It might still happen that manual intervention is required
(e.g. because the repo is corrupt), but at the very least it won't
be because Git is too dumb to try again.
Signed-off-by: David Turner <dturner@twosigma.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-02-11 00:28:22 +03:00
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test_config gc.logexpiry 5.days &&
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2018-03-24 10:44:31 +03:00
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test-tool chmtime =-345600 .git/gc.log &&
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gc: do not return error for prior errors in daemonized mode
Some build machines started consistently failing to fetch updated
source using "repo sync", with error
error: The last gc run reported the following. Please correct the root cause
and remove /build/.repo/projects/tools/git.git/gc.log.
Automatic cleanup will not be performed until the file is removed.
warning: There are too many unreachable loose objects; run 'git prune' to remove them.
The cause takes some time to describe.
In v2.0.0-rc0~145^2 (gc: config option for running --auto in
background, 2014-02-08), "git gc --auto" learned to run in the
background instead of blocking the invoking command. In this mode, it
closed stderr to avoid interleaving output with any subsequent
commands, causing warnings like the above to be swallowed; v2.6.3~24^2
(gc: save log from daemonized gc --auto and print it next time,
2015-09-19) addressed that by storing any diagnostic output in
.git/gc.log and allowing the next "git gc --auto" run to print it.
To avoid wasteful repeated fruitless gcs, when gc.log is present, the
subsequent "gc --auto" would die after printing its contents. Most
git commands, such as "git fetch", ignore the exit status from "git gc
--auto" so all is well at this point: the user gets to see the error
message, and the fetch succeeds, without a wasteful additional attempt
at an automatic gc.
External tools like repo[1], though, do care about the exit status
from "git gc --auto". In non-daemonized mode, the exit status is
straightforward: if there is an error, it is nonzero, but after a
warning like the above, the status is zero. The daemonized mode, as a
side effect of the other properties provided, offers a very strange
exit code convention:
- if no housekeeping was required, the exit status is 0
- the first real run, after forking into the background, returns exit
status 0 unconditionally. The parent process has no way to know
whether gc will succeed.
- if there is any diagnostic output in gc.log, subsequent runs return
a nonzero exit status to indicate that gc was not triggered.
There's nothing for the calling program to act on on the basis of that
error. Use status 0 consistently instead, to indicate that we decided
not to run a gc (just like if no housekeeping was required). This
way, repo and similar tools can get the benefit of the same behavior
as tools like "git fetch" that ignore the exit status from gc --auto.
Once the period of time described by gc.pruneExpire elapses, the
unreachable loose objects will be removed by "git gc --auto"
automatically.
[1] https://gerrit-review.googlesource.com/c/git-repo/+/10598/
Reported-by: Andrii Dehtiarov <adehtiarov@google.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-07-17 09:57:40 +03:00
|
|
|
git gc --auto &&
|
gc: ignore old gc.log files
A server can end up in a state where there are lots of unreferenced
loose objects (say, because many users are doing a bunch of rebasing
and pushing their rebased branches). Running "git gc --auto" in
this state would cause a gc.log file to be created, preventing
future auto gcs, causing pack files to pile up. Since many git
operations are O(n) in the number of pack files, this would lead to
poor performance.
Git should never get itself into a state where it refuses to do any
maintenance, just because at some point some piece of the maintenance
didn't make progress.
Teach Git to ignore gc.log files which are older than (by default)
one day old, which can be tweaked via the gc.logExpiry configuration
variable. That way, these pack files will get cleaned up, if
necessary, at least once per day. And operators who find a need for
more-frequent gcs can adjust gc.logExpiry to meet their needs.
There is also some cleanup: a successful manual gc, or a
warning-free auto gc with an old log file, will remove any old
gc.log files.
It might still happen that manual intervention is required
(e.g. because the repo is corrupt), but at the very least it won't
be because Git is too dumb to try again.
Signed-off-by: David Turner <dturner@twosigma.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-02-11 00:28:22 +03:00
|
|
|
test_config gc.logexpiry 2.days &&
|
t6500: wait for detached auto gc at the end of the test script
The last test in 't6500-gc', 'background auto gc does not run if
gc.log is present and recent but does if it is old', added in
a831c06a2 (gc: ignore old gc.log files, 2017-02-10), may sporadically
trigger an error message from the test harness:
rm: cannot remove 'trash directory.t6500-gc/.git/objects': Directory not empty
The test in question ends with executing an auto gc in the backround,
which occasionally takes so long that it's still running when
'test_done' is about to remove the trash directory. This 'rm -rf
$trash' in the foreground might race with the detached auto gc to
create and delete files and directories, and gc might (re-)create a
path that 'rm' already visited and removed, triggering the above error
message when 'rm' attempts to remove its parent directory.
Commit bb05510e5 (t5510: run auto-gc in the foreground, 2016-05-01)
fixed the same problem in a different test script by simply
disallowing background gc. Unfortunately, what worked there is not
applicable here, because the purpose of this test is to check the
behavior of a detached auto gc.
Make sure that the test doesn't continue before the gc is finished in
the background with a clever bit of shell trickery:
- Open fd 9 in the shell, to be inherited by the background gc
process, because our daemonize() only closes the standard fds 0,
1 and 2.
- Duplicate this fd 9 to stdout.
- Read 'git gc's stdout, and thus fd 9, through a command
substitution. We don't actually care about gc's output, but this
construct has two useful properties:
- This read blocks until stdout or fd 9 are open. While stdout is
closed after the main gc process creates the background process
and exits, fd 9 remains open until the backround process exits.
- The variable assignment from the command substitution gets its
exit status from the command executed within the command
substitution, i.e. a failing main gc process will cause the test
to fail.
Note, that this fd trickery doesn't work on Windows, because due to
MSYS limitations the git process only inherits the standard fds 0, 1
and 2 from the shell. Luckily, it doesn't matter in this case,
because on Windows daemonize() is basically a noop, thus 'git gc
--auto' always runs in the foreground.
And since we can now continue the test reliably after the detached gc
finished, check that there is only a single packfile left at the end,
i.e. that the detached gc actually did what it was supposed to do.
Also add a comment at the end of the test script to warn developers of
future tests about this issue of long running detached gc processes.
Helped-by: Jeff King <peff@peff.net>
Helped-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-04-13 13:31:38 +03:00
|
|
|
run_and_wait_for_auto_gc &&
|
|
|
|
|
ls .git/objects/pack/pack-*.pack >packs &&
|
|
|
|
|
test_line_count = 1 packs
|
gc: ignore old gc.log files
A server can end up in a state where there are lots of unreferenced
loose objects (say, because many users are doing a bunch of rebasing
and pushing their rebased branches). Running "git gc --auto" in
this state would cause a gc.log file to be created, preventing
future auto gcs, causing pack files to pile up. Since many git
operations are O(n) in the number of pack files, this would lead to
poor performance.
Git should never get itself into a state where it refuses to do any
maintenance, just because at some point some piece of the maintenance
didn't make progress.
Teach Git to ignore gc.log files which are older than (by default)
one day old, which can be tweaked via the gc.logExpiry configuration
variable. That way, these pack files will get cleaned up, if
necessary, at least once per day. And operators who find a need for
more-frequent gcs can adjust gc.logExpiry to meet their needs.
There is also some cleanup: a successful manual gc, or a
warning-free auto gc with an old log file, will remove any old
gc.log files.
It might still happen that manual intervention is required
(e.g. because the repo is corrupt), but at the very least it won't
be because Git is too dumb to try again.
Signed-off-by: David Turner <dturner@twosigma.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-02-11 00:28:22 +03:00
|
|
|
'
|
2016-12-29 01:45:41 +03:00
|
|
|
|
gc: run pre-detach operations under lock
We normally try to avoid having two auto-gc operations run
at the same time, because it wastes resources. This was done
long ago in 64a99eb47 (gc: reject if another gc is running,
unless --force is given, 2013-08-08).
When we do a detached auto-gc, we run the ref-related
commands _before_ detaching, to avoid confusing lock
contention. This was done by 62aad1849 (gc --auto: do not
lock refs in the background, 2014-05-25).
These two features do not interact well. The pre-detach
operations are run before we check the gc.pid lock, meaning
that on a busy repository we may run many of them
concurrently. Ideally we'd take the lock before spawning any
operations, and hold it for the duration of the program.
This is tricky, though, with the way the pid-file interacts
with the daemonize() process. Other processes will check
that the pid recorded in the pid-file still exists. But
detaching causes us to fork and continue running under a
new pid. So if we take the lock before detaching, the
pid-file will have a bogus pid in it. We'd have to go back
and update it with the new pid after detaching. We'd also
have to play some tricks with the tempfile subsystem to
tweak the "owner" field, so that the parent process does not
clean it up on exit, but the child process does.
Instead, we can do something a bit simpler: take the lock
only for the duration of the pre-detach work, then detach,
then take it again for the post-detach work. Technically,
this means that the post-detach lock could lose to another
process doing pre-detach work. But in the long run this
works out.
That second process would then follow-up by doing
post-detach work. Unless it was in turn blocked by a third
process doing pre-detach work, and so on. This could in
theory go on indefinitely, as the pre-detach work does not
repack, and so need_to_gc() will continue to trigger. But
in each round we are racing between the pre- and post-detach
locks. Eventually, one of the post-detach locks will win the
race and complete the full gc. So in the worst case, we may
racily repeat the pre-detach work, but we would never do so
simultaneously (it would happen via a sequence of serialized
race-wins).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-07-11 12:06:35 +03:00
|
|
|
test_expect_success 'background auto gc respects lock for all operations' '
|
|
|
|
|
# make sure we run a background auto-gc
|
|
|
|
|
test_commit make-pack &&
|
|
|
|
|
git repack &&
|
|
|
|
|
test_config gc.autopacklimit 1 &&
|
|
|
|
|
test_config gc.autodetach true &&
|
|
|
|
|
|
|
|
|
|
# create a ref whose loose presence we can use to detect a pack-refs run
|
|
|
|
|
git update-ref refs/heads/should-be-loose HEAD &&
|
|
|
|
|
test_path_is_file .git/refs/heads/should-be-loose &&
|
|
|
|
|
|
|
|
|
|
# now fake a concurrent gc that holds the lock; we can use our
|
|
|
|
|
# shell pid so that it looks valid.
|
|
|
|
|
hostname=$(hostname || echo unknown) &&
|
2019-05-08 00:51:30 +03:00
|
|
|
shell_pid=$$ &&
|
|
|
|
|
if test_have_prereq MINGW && test -f /proc/$shell_pid/winpid
|
|
|
|
|
then
|
|
|
|
|
# In Git for Windows, Bash (actually, the MSYS2 runtime) has a
|
|
|
|
|
# different idea of PIDs than git.exe (actually Windows). Use
|
|
|
|
|
# the Windows PID in this case.
|
|
|
|
|
shell_pid=$(cat /proc/$shell_pid/winpid)
|
|
|
|
|
fi &&
|
|
|
|
|
printf "%d %s" "$shell_pid" "$hostname" >.git/gc.pid &&
|
gc: run pre-detach operations under lock
We normally try to avoid having two auto-gc operations run
at the same time, because it wastes resources. This was done
long ago in 64a99eb47 (gc: reject if another gc is running,
unless --force is given, 2013-08-08).
When we do a detached auto-gc, we run the ref-related
commands _before_ detaching, to avoid confusing lock
contention. This was done by 62aad1849 (gc --auto: do not
lock refs in the background, 2014-05-25).
These two features do not interact well. The pre-detach
operations are run before we check the gc.pid lock, meaning
that on a busy repository we may run many of them
concurrently. Ideally we'd take the lock before spawning any
operations, and hold it for the duration of the program.
This is tricky, though, with the way the pid-file interacts
with the daemonize() process. Other processes will check
that the pid recorded in the pid-file still exists. But
detaching causes us to fork and continue running under a
new pid. So if we take the lock before detaching, the
pid-file will have a bogus pid in it. We'd have to go back
and update it with the new pid after detaching. We'd also
have to play some tricks with the tempfile subsystem to
tweak the "owner" field, so that the parent process does not
clean it up on exit, but the child process does.
Instead, we can do something a bit simpler: take the lock
only for the duration of the pre-detach work, then detach,
then take it again for the post-detach work. Technically,
this means that the post-detach lock could lose to another
process doing pre-detach work. But in the long run this
works out.
That second process would then follow-up by doing
post-detach work. Unless it was in turn blocked by a third
process doing pre-detach work, and so on. This could in
theory go on indefinitely, as the pre-detach work does not
repack, and so need_to_gc() will continue to trigger. But
in each round we are racing between the pre- and post-detach
locks. Eventually, one of the post-detach locks will win the
race and complete the full gc. So in the worst case, we may
racily repeat the pre-detach work, but we would never do so
simultaneously (it would happen via a sequence of serialized
race-wins).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-07-11 12:06:35 +03:00
|
|
|
|
|
|
|
|
# our gc should exit zero without doing anything
|
|
|
|
|
run_and_wait_for_auto_gc &&
|
|
|
|
|
test_path_is_file .git/refs/heads/should-be-loose
|
|
|
|
|
'
|
|
|
|
|
|
t6500: wait for detached auto gc at the end of the test script
The last test in 't6500-gc', 'background auto gc does not run if
gc.log is present and recent but does if it is old', added in
a831c06a2 (gc: ignore old gc.log files, 2017-02-10), may sporadically
trigger an error message from the test harness:
rm: cannot remove 'trash directory.t6500-gc/.git/objects': Directory not empty
The test in question ends with executing an auto gc in the backround,
which occasionally takes so long that it's still running when
'test_done' is about to remove the trash directory. This 'rm -rf
$trash' in the foreground might race with the detached auto gc to
create and delete files and directories, and gc might (re-)create a
path that 'rm' already visited and removed, triggering the above error
message when 'rm' attempts to remove its parent directory.
Commit bb05510e5 (t5510: run auto-gc in the foreground, 2016-05-01)
fixed the same problem in a different test script by simply
disallowing background gc. Unfortunately, what worked there is not
applicable here, because the purpose of this test is to check the
behavior of a detached auto gc.
Make sure that the test doesn't continue before the gc is finished in
the background with a clever bit of shell trickery:
- Open fd 9 in the shell, to be inherited by the background gc
process, because our daemonize() only closes the standard fds 0,
1 and 2.
- Duplicate this fd 9 to stdout.
- Read 'git gc's stdout, and thus fd 9, through a command
substitution. We don't actually care about gc's output, but this
construct has two useful properties:
- This read blocks until stdout or fd 9 are open. While stdout is
closed after the main gc process creates the background process
and exits, fd 9 remains open until the backround process exits.
- The variable assignment from the command substitution gets its
exit status from the command executed within the command
substitution, i.e. a failing main gc process will cause the test
to fail.
Note, that this fd trickery doesn't work on Windows, because due to
MSYS limitations the git process only inherits the standard fds 0, 1
and 2 from the shell. Luckily, it doesn't matter in this case,
because on Windows daemonize() is basically a noop, thus 'git gc
--auto' always runs in the foreground.
And since we can now continue the test reliably after the detached gc
finished, check that there is only a single packfile left at the end,
i.e. that the detached gc actually did what it was supposed to do.
Also add a comment at the end of the test script to warn developers of
future tests about this issue of long running detached gc processes.
Helped-by: Jeff King <peff@peff.net>
Helped-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-04-13 13:31:38 +03:00
|
|
|
# DO NOT leave a detached auto gc process running near the end of the
|
|
|
|
|
# test script: it can run long enough in the background to racily
|
|
|
|
|
# interfere with the cleanup in 'test_done'.
|
|
|
|
|
|
2010-10-22 10:47:19 +04:00
|
|
|
test_done
|
