"git repack" learned "--max-cruft-size" to prevent cruft packs from
growing without bounds.
* tb/repack-max-cruft-size:
repack: free existing_cruft array after use
builtin/repack.c: avoid making cruft packs preferred
builtin/repack.c: implement support for `--max-cruft-size`
builtin/repack.c: parse `--max-pack-size` with OPT_MAGNITUDE
t7700: split cruft-related tests to t7704
Cruft packs are an alternative mechanism for storing a collection of
unreachable objects whose mtimes are recent enough to avoid being
pruned out of the repository.
When cruft packs were first introduced back in b757353676
(builtin/pack-objects.c: --cruft without expiration, 2022-05-20) and
a7d493833f (builtin/pack-objects.c: --cruft with expiration,
2022-05-20), the recommended workflow consisted of:
- Repacking periodically, either by packing anything loose in the
repository (via `git repack -d`) or producing a geometric sequence
of packs (via `git repack --geometric=<d> -d`).
- Every so often, splitting the repository into two packs, one cruft
to store the unreachable objects, and another non-cruft pack to
store the reachable objects.
Repositories may (out of band with the above) choose periodically to
prune out some unreachable objects which have aged out of the grace
period by generating a pack with `--cruft-expiration=<approxidate>`.
This allowed repositories to maintain relatively few packs on average,
and quarantine unreachable objects together in a cruft pack, avoiding
the pitfalls of holding unreachable objects as loose while they age out
(for more, see some of the details in 3d89a8c118
(Documentation/technical: add cruft-packs.txt, 2022-05-20)).
This all works, but can be costly from an I/O-perspective when
frequently repacking a repository that has many unreachable objects.
This problem is exacerbated when those unreachable objects are rarely
(if every) pruned.
Since there is at most one cruft pack in the above scheme, each time we
update the cruft pack it must be rewritten from scratch. Because much of
the pack is reused, this is a relatively inexpensive operation from a
CPU-perspective, but is very costly in terms of I/O since we end up
rewriting basically the same pack (plus any new unreachable objects that
have entered the repository since the last time a cruft pack was
generated).
At the time, we decided against implementing more robust support for
multiple cruft packs. This patch implements that support which we were
lacking.
Introduce a new option `--max-cruft-size` which allows repositories to
accumulate cruft packs up to a given size, after which point a new
generation of cruft packs can accumulate until it reaches the maximum
size, and so on. To generate a new cruft pack, the process works like
so:
- Sort a list of any existing cruft packs in ascending order of pack
size.
- Starting from the beginning of the list, group cruft packs together
while the accumulated size is smaller than the maximum specified
pack size.
- Combine the objects in these cruft packs together into a new cruft
pack, along with any other unreachable objects which have since
entered the repository.
Once a cruft pack grows beyond the size specified via `--max-cruft-size`
the pack is effectively frozen. This limits the I/O churn up to a
quadratic function of the value specified by the `--max-cruft-size`
option, instead of behaving quadratically in the number of total
unreachable objects.
When pruning unreachable objects, we bypass the new code paths which
combine small cruft packs together, and instead start from scratch,
passing in the appropriate `--max-pack-size` down to `pack-objects`,
putting it in charge of keeping the resulting set of cruft packs sized
correctly.
This may seem like further I/O churn, but in practice it isn't so bad.
We could prune old cruft packs for whom all or most objects are removed,
and then generate a new cruft pack with just the remaining set of
objects. But this additional complexity buys us relatively little,
because most objects end up being pruned anyway, so the I/O churn is
well contained.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A previous commit implemented the `gc.repackFilter` config option
to specify a filter that should be used by `git gc` when
performing repacks.
Another previous commit has implemented
`git repack --filter-to=<dir>` to specify the location of the
packfile containing filtered out objects when using a filter.
Let's implement the `gc.repackFilterTo` config option to specify
that location in the config when `gc.repackFilter` is used.
Now when `git gc` will perform a repack with a <dir> configured
through this option and not empty, the repack process will be
passed a corresponding `--filter-to=<dir>` argument.
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A previous commit has implemented `git repack --filter=<filter-spec>` to
allow users to filter out some objects from the main pack and move them
into a new different pack.
Users might want to perform such a cleanup regularly at the same time as
they perform other repacks and cleanups, so as part of `git gc`.
Let's allow them to configure a <filter-spec> for that purpose using a
new gc.repackFilter config option.
Now when `git gc` will perform a repack with a <filter-spec> configured
through this option and not empty, the repack process will be passed a
corresponding `--filter=<filter-spec>` argument.
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Back in 5b92477f89 (builtin/gc.c: conditionally avoid pruning objects
via loose, 2022-05-20), `git gc` learned the `--cruft` option and
`gc.cruftPacks` configuration to opt-in to writing cruft packs when
collecting or pruning unreachable objects.
Cruft packs were introduced with the merge in a50036da1a (Merge branch
'tb/cruft-packs', 2022-06-03). They address the problem of "loose object
explosions", where Git will write out many individual loose objects when
there is a large number of unreachable objects that have not yet aged
past `--prune=<date>`.
Instead of keeping track of those unreachable yet recent objects via
their loose object file's mtime, cruft packs collect all unreachable
objects into a single pack with a corresponding `*.mtimes` file that
acts as a table to store the mtimes of all unreachable objects. This
prevents the need to store unreachable objects as loose as they age out
of the repository, and avoids the problem of loose object explosions.
Beyond avoiding loose object explosions, cruft packs also act as a more
efficient mechanism to store unreachable objects as they age out of a
repository. This is because pairs of similar unreachable objects serve
as delta bases for one another.
In 5b92477f89, the feature was introduced as experimental. Since then,
GitHub has been running these patches in every repository generating
hundreds of millions of cruft packs along the way. The feature is
battle-tested, and avoids many pathological cases such as above. Users
who either run `git gc` manually, or via `git maintenance` can benefit
from having cruft packs.
As such, enable cruft pack generation to take place by default (by
making `gc.cruftPacks` have the default of "true" rather than "false).
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the last commit, we refactored some of the tests in t6500 to make
clearer when cruft packs will and won't be generated by `git gc`.
Add the remaining cases not covered by the previous patch into this one,
which enumerates all possible combinations of arguments that will
produce (or not produce) a cruft pack.
This prepares us for a future commit which will change the default value
of `gc.cruftPacks` by ensuring that we understand which invocations do
and do not change as a result.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 12253ab6d0 (gc: add tests for --cruft and friends, 2022-10-26), we
added a handful of tests to t6500 to ensure that `git gc` respected the
value of `--cruft` and `gc.cruftPacks`.
Then, in c695592850 (config: let feature.experimental imply
gc.cruftPacks=true, 2022-10-26), another set of similar tests was added
to ensure that `feature.experimental` correctly implied enabling cruft
pack generation (or not).
These tests are similar and could be consolidated. Do so in this patch
to prepare for expanding the set of command-line invocations that enable
or disable writing cruft packs. This makes it possible to easily test
more combinations of arguments without being overly repetitive.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When cruft packs were implemented, we never adjusted the code for `git
gc`'s `--keep-largest-pack` and `gc.bigPackThreshold` to ignore cruft
packs. This option and configuration option share a common
implementation, but including cruft packs is wrong in both cases:
- Running `git gc --keep-largest-pack` in a repository where the
largest pack is the cruft pack itself will make it impossible for
`git gc` to prune objects, since the cruft pack itself is kept.
- The same is true for `gc.bigPackThreshold`, if the size of the cruft
pack exceeds the limit set by the caller.
In the future, it is possible that `gc.bigPackThreshold` could be used
to write a separate cruft pack containing any new unreachable objects
that entered the repository since the last time a cruft pack was
written.
There are some complexities to doing so, mainly around handling
pruning objects that are in an existing cruft pack that is above the
threshold (which would either need to be rewritten, or else delay
pruning). Rewriting a substantially similar cruft pack isn't ideal, but
it is significantly better than the status-quo.
If users have large cruft packs that they don't want to rewrite, they
can mark them as `*.keep` packs. But in general, if a repository has a
cruft pack that is so large it is slowing down GC's, it should probably
be pruned anyway.
In the meantime, ignore cruft packs in the common implementation for
both of these options, and add a pair of tests to prevent any future
regressions here.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We are interested in exploring whether gc.cruftPacks=true should become
the default value.
To determine whether it is safe to do so, let's encourage more users to
try it out.
Users who have set feature.experimental=true have already volunteered to
try new and possibly-breaking config changes, so let's try this new
default with that set of users.
Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 5b92477f89 (builtin/gc.c: conditionally avoid pruning objects via
loose, 2022-05-20) gc learned to respect '--cruft' and 'gc.cruftPacks'.
'--cruft' is exercised in t5329-pack-objects-cruft.sh, but in a way that
doesn't check whether a lone gc run generates these cruft packs.
'gc.cruftPacks' is never exercised.
Add some tests to exercise these options to gc in the gc test suite.
Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Refactor the repository setup code for tests that test hooks the use
of sub-shells when setting up the test repository and hooks, and use
the "test_hook" wrapper instead of "write_scripts".
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
By doing ls -1 .git/{reftable,refs/heads}, we can capture changes to both
reftable and packed/loose ref storage.
This relies on the fact that git-pack-refs (which we're looking for here)
changes the number (loose/packed storage) and/or names (reftable) files used for
ref storage.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a missing test for the behavior of the pre-auto-gc hook added in
0b85d92661 (Documentation/hooks: add pre-auto-gc hook, 2008-04-02).
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Test framework clean-up.
* ab/test-lib:
test-lib-functions: assert correct parameter count
test-lib-functions: remove bug-inducing "diagnostics" helper param
test libs: rename "diff-lib" to "lib-diff"
t/.gitattributes: sort lines
test-lib-functions: move function to lib-bitmap.sh
test libs: rename gitweb-lib.sh to lib-gitweb.sh
test libs: rename bundle helper to "lib-bundle.sh"
test-lib-functions: remove generate_zero_bytes() wrapper
test-lib-functions: move test_set_index_version() to its user
test lib: change "error" to "BUG" as appropriate
test-lib: remove check_var_migration
Remove the optional "diagnostics" parameter of the
test_path_is_{file,dir,missing} functions.
We have a lot of uses of these functions, but the only legitimate use
of the diagnostics parameter is from when the functions themselves
were introduced in 2caf20c52b (test-lib: user-friendly alternatives
to test [-d|-f|-e], 2010-08-10).
But as the the rest of this diff demonstrates its presence did more to
silently introduce bugs in our tests. Fix such bugs in the tests added
in ae4e89e549 (gc: add --keep-largest-pack option, 2018-04-15), and
c04ba51739 (t6046: testcases checking whether updates can be skipped
in a merge, 2018-04-19).
Let's also assert that those functions are called with exactly one
parameter, a follow-up commit will add similar asserts to other
functions in test-lib-functions.sh that we didn't have existing misuse
of.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the next patch, we'll add support for unconditionally enabling the
'pack.writeReverseIndex' setting with a new GIT_TEST_WRITE_REV_INDEX
environment variable.
This causes a little bit of fallout with tests that, for example,
compare the list of files in the pack directory being unprepared to see
.rev files in its output.
Those locations can be cleaned up to look for specific file extensions,
rather than take everything in the pack directory (for instance) and
then grep out unwanted items.
Once the pack.writeReverseIndex option has been thoroughly
tested, we will default it to 'true', removing GIT_TEST_WRITE_REV_INDEX,
and making it possible to revert this patch.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In this test, we want to produce several blobs whose first two hex
characters are "17", since we look at this object directory as a proxy
for how many loose objects there are before we need to GC. Use
test_oid_cache to specify strings that will hash to the right values
when turned into blobs.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When writing a commit-graph, we show progress along several commit
walks. When we use start_delayed_progress(), the progress line will
only appear if that step takes a decent amount of time.
However, one place was missed: computing generation numbers. This is
normally a very fast operation as all commits have been parsed in a
previous step. But, this is showing up for all users no matter how few
commits are being added.
The tests that check for the progress output have already been updated
to use GIT_PROGRESS_DELAY=0 to force the expected output.
Helped-by: Jeff King <peff@peff.net>
Reported-by: ryenus <ryenus@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The start_delayed_progress() method is a preferred way to show
optional progress to users as it ignores steps that take less
than two seconds. However, this makes testing unreliable as tests
expect to be very fast.
In addition, users may want to decrease or increase this time
interval depending on their preferences for terminal noise.
Create the GIT_PROGRESS_DELAY environment variable to control
the delay set during start_delayed_progress(). Set the value
in some tests to guarantee their output remains consistent.
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Having non-existent packs in objects/info/packs causes
dumb HTTP clients to abort.
v2: use single loop with ALLOC_GROW as suggested by Jeff King
Signed-off-by: Eric Wong <e@80x24.org>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Future-proof a test against an update to MSYS2 runtime v3.x series.
* js/t6500-use-windows-pid-on-mingw:
t6500(mingw): use the Windows PID of the shell
In Git for Windows, we use the MSYS2 Bash which inherits a non-standard
PID model from Cygwin's POSIX emulation layer: every MSYS2 process has a
regular Windows PID, and in addition it has an MSYS2 PID (which
corresponds to a shadow process that emulates Unix-style signal
handling).
With the upgrade to the MSYS2 runtime v3.x, this shadow process cannot
be accessed via `OpenProcess()` any longer, and therefore t6500 thought
incorrectly that the process referenced in `gc.pid` (which is not
actually a real `gc` process in this context, but the current shell) no
longer exists.
Let's fix this by making sure that the Windows PID is written into
`gc.pid` in this test script so that `git.exe` is able to understand
that that process does indeed still exist.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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>
"gc --auto" ended up calling exit(-1) upon error, which has been
corrected to use exit(1). Also the error reporting behaviour when
daemonized has been updated to exit with zero status when stopping
due to a previously discovered error (which implies there is no
point running gc to improve the situation); we used to exit with
failure in such a case.
* jn/gc-auto:
gc: do not return error for prior errors in daemonized mode
Fix a regression in my recent 7b0f229222 ("commit-graph write: add
progress output", 2018-09-17). The newly added progress output for
"commit-graph write" didn't check the --quiet option.
Do so, and add a test asserting that this works as expected. Since the
TTY prequisite isn't available everywhere let's add a version of this
that both requires and doesn't require that. This test might be overly
specific and will break if new progress output is added, but I think
it'll serve as a good reminder to test the undertested progress
mode(s).
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Helped-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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>
A value of -1 returned from cmd_gc gets propagated to exit(),
resulting in an exit status of 255. Use die instead for a clearer
error message and a controlled exit.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
pack-objects could be a big memory hog especially on large repos,
everybody knows that. The suggestion to stick a .keep file on the
giant base pack to avoid this problem is also known for a long time.
Recent patches add an option to do just this, but it has to be either
configured or activated manually. This patch lets `git gc --auto`
activate this mode automatically when it thinks `repack -ad` will use
a lot of memory and start affecting the system due to swapping or
flushing OS cache.
gc --auto decides to do this based on an estimation of pack-objects
memory usage, which is quite accurate at least for the heap part, and
whether that fits in half of system memory (the assumption here is for
desktop environment where there are many other applications running).
This mechanism only kicks in if gc.bigBasePackThreshold is not configured.
If it is, it is assumed that the user already knows what they want.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This adds a new repack mode that combines everything into a secondary
pack, leaving the largest pack alone.
This could help reduce memory pressure. On linux-2.6.git, valgrind
massif reports 1.6GB heap in "pack all" case, and 535MB in "pack
all except the base pack" case. We save roughly 1GB memory by
excluding the base pack.
This should also lower I/O because we don't have to rewrite a giant
pack every time (e.g. for linux-2.6.git that's a 1.4GB pack file)..
PS. The use of string_list here seems overkill, but we'll need it in
the next patch...
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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>
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>
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>
When git gc --auto does an incremental repack of loose objects, we do
not expect to be able to write a bitmap; it is very likely that
objects in the new pack will have references to objects outside of the
pack. So we shouldn't try to write a bitmap, because doing so will
likely issue a warning.
This warning was making its way into gc.log. When the gc.log was
present, future auto gc runs would refuse to run.
Patch by Jeff King.
Bug report, test, and commit message by David Turner.
Signed-off-by: David Turner <dturner@twosigma.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It is quite possible for, say, a remote HEAD to become broken, e.g.
when the default branch was renamed.
We should still be able to pack our objects when such a thing happens;
simply ignore broken symrefs (because they cannot matter for the packing
process anyway).
This fixes https://github.com/git-for-windows/git/issues/423
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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>
Use the i18n-specific test functions in test scripts for parseopt tests.
This issue was was introduced in v1.7.10.1-488-g54e6d:
54e6d i18n: parseopt: lookup help and argument translations when showing usage
and been broken under GETTEXT_POISON=YesPlease since.
Signed-off-by: Jiang Xin <worldhello.net@gmail.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Given a request for command-line usage information rather than some
more substantial action, the only friendly thing to do is to report
the usage information as soon as possible and exit.
Without this change, as "git gc" glances over the repository, it can
be distracted by the desire to report a malformed configuration file.
Noticed while working through reports from Duy's repository access
checker.
[jn: with rewritten log message and tests]
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
