| Message ID | bfda40a21ddb7abceb6a7eb9aa1f71aa5d856333.1681764848.git.me@ttaylorr.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | gc: enable cruft packs by default | expand |
On Mon, Apr 17, 2023 at 04:54:39PM -0400, Taylor Blau wrote: > for argv in \ > + "gc" \ > "gc --cruft" \ > "-c gc.cruftPacks=true gc" \ > - "-c gc.cruftPacks=false gc --cruft" \ > - "-c feature.experimental=true gc" \ > - "-c gc.cruftPacks=true -c feature.experimental=false gc" > + "-c gc.cruftPacks=false gc --cruft" > do Oh good. I was a little sad to see the increase in the size of this loop in the earlier patches, so now reducing the number of combinations is a welcome change. The set you have here looks fine, though isn't "gc --cruft" redundant with "gc" now? > @@ -246,9 +245,7 @@ done > for argv in \ > "gc --no-cruft" \ > "-c gc.cruftPacks=false gc" \ > - "-c gc.cruftPacks=true gc --no-cruft" \ > - "-c feature.expiremental=true -c gc.cruftPacks=false gc" \ > - "-c feature.experimental=false gc" > + "-c gc.cruftPacks=true gc --no-cruft" Likewise here, "gc --no-cruft" would have been redundant with "gc" before this patch, but we did not even bother with it (so no need to remove it here!). The rest of the patch looks good, and I am quite on board with the overall goal. It's been a long time coming. :) -Peff
On Tue, Apr 18, 2023 at 07:00:49AM -0400, Jeff King wrote: > On Mon, Apr 17, 2023 at 04:54:39PM -0400, Taylor Blau wrote: > > > for argv in \ > > + "gc" \ > > "gc --cruft" \ > > "-c gc.cruftPacks=true gc" \ > > - "-c gc.cruftPacks=false gc --cruft" \ > > - "-c feature.experimental=true gc" \ > > - "-c gc.cruftPacks=true -c feature.experimental=false gc" > > + "-c gc.cruftPacks=false gc --cruft" > > do > > Oh good. I was a little sad to see the increase in the size of this loop > in the earlier patches, so now reducing the number of combinations is a > welcome change. Sorry for the roller-coaster of emotions ;-). > The set you have here looks fine, though isn't "gc --cruft" redundant > with "gc" now? Yeah, these are redundant. I figured that it might be good to test all cases, but I think this matrix-style of testing only gets you so far, and can often come out wasteful. "gc --cruft" isn't testing anything meaningful, so let's drop it. > > @@ -246,9 +245,7 @@ done > > for argv in \ > > "gc --no-cruft" \ > > "-c gc.cruftPacks=false gc" \ > > - "-c gc.cruftPacks=true gc --no-cruft" \ > > - "-c feature.expiremental=true -c gc.cruftPacks=false gc" \ > > - "-c feature.experimental=false gc" > > + "-c gc.cruftPacks=true gc --no-cruft" > > Likewise here, "gc --no-cruft" would have been redundant with "gc" > before this patch, but we did not even bother with it (so no need to > remove it here!). Yeah, this one we definitely want to keep. We probably *could* have dropped it in the previous patch and brought it back here, but I think that doing so would have been unnecessary churn for reviewers reading this series. > The rest of the patch looks good, and I am quite on board with the > overall goal. It's been a long time coming. :) Thanks, I agree ;-). Thanks, Taylor
diff --git a/Documentation/config/feature.txt b/Documentation/config/feature.txt index e52bc6b858..17b4d39f89 100644 --- a/Documentation/config/feature.txt +++ b/Documentation/config/feature.txt @@ -14,9 +14,6 @@ feature.experimental:: + * `fetch.negotiationAlgorithm=skipping` may improve fetch negotiation times by skipping more commits at a time, reducing the number of round trips. -+ -* `gc.cruftPacks=true` reduces disk space used by unreachable objects during -garbage collection, preventing loose object explosions. feature.manyFiles:: Enable config options that optimize for repos with many files in the diff --git a/Documentation/config/gc.txt b/Documentation/config/gc.txt index 8d5353e9e0..7f95c866e1 100644 --- a/Documentation/config/gc.txt +++ b/Documentation/config/gc.txt @@ -84,7 +84,7 @@ gc.packRefs:: gc.cruftPacks:: Store unreachable objects in a cruft pack (see linkgit:git-repack[1]) instead of as loose objects. The default - is `false`. + is `true`. gc.pruneExpire:: When 'git gc' is run, it will call 'prune --expire 2.weeks.ago' diff --git a/Documentation/git-gc.txt b/Documentation/git-gc.txt index 2427478314..0b4e7ba882 100644 --- a/Documentation/git-gc.txt +++ b/Documentation/git-gc.txt @@ -54,9 +54,10 @@ other housekeeping tasks (e.g. rerere, working trees, reflog...) will be performed as well. ---cruft:: +--[no-]cruft:: When expiring unreachable objects, pack them separately into a - cruft pack instead of storing them as loose objects. + cruft pack instead of storing them as loose objects. `--cruft` + is on by default. --prune=<date>:: Prune loose objects older than date (default is 2 weeks ago, diff --git a/Documentation/gitformat-pack.txt b/Documentation/gitformat-pack.txt index e06af02f21..0c1be2dbe8 100644 --- a/Documentation/gitformat-pack.txt +++ b/Documentation/gitformat-pack.txt @@ -611,8 +611,8 @@ result of repeatedly resetting the objects' mtimes to the present time. If you are GC-ing repositories in a mixed version environment, consider omitting the `--cruft` option when using linkgit:git-repack[1] and linkgit:git-gc[1], and -leaving the `gc.cruftPacks` configuration unset until all writers understand -cruft packs. +setting the `gc.cruftPacks` configuration to "false" until all writers +understand cruft packs. === Alternatives diff --git a/builtin/gc.c b/builtin/gc.c index 53ef137e1d..ece01e966f 100644 --- a/builtin/gc.c +++ b/builtin/gc.c @@ -48,7 +48,7 @@ static const char * const builtin_gc_usage[] = { static int pack_refs = 1; static int prune_reflogs = 1; -static int cruft_packs = -1; +static int cruft_packs = 1; static int aggressive_depth = 50; static int aggressive_window = 250; static int gc_auto_threshold = 6700; @@ -608,10 +608,6 @@ int cmd_gc(int argc, const char **argv, const char *prefix) if (prune_expire && parse_expiry_date(prune_expire, &dummy)) die(_("failed to parse prune expiry value %s"), prune_expire); - prepare_repo_settings(the_repository); - if (cruft_packs < 0) - cruft_packs = the_repository->settings.gc_cruft_packs; - if (aggressive) { strvec_push(&repack, "-f"); if (aggressive_depth > 0) diff --git a/t/t6500-gc.sh b/t/t6500-gc.sh index e7d3d1448f..75760866b4 100755 --- a/t/t6500-gc.sh +++ b/t/t6500-gc.sh @@ -216,11 +216,10 @@ assert_no_cruft_packs () { } for argv in \ + "gc" \ "gc --cruft" \ "-c gc.cruftPacks=true gc" \ - "-c gc.cruftPacks=false gc --cruft" \ - "-c feature.experimental=true gc" \ - "-c gc.cruftPacks=true -c feature.experimental=false gc" + "-c gc.cruftPacks=false gc --cruft" do test_expect_success "git $argv generates a cruft pack" ' test_when_finished "rm -fr repo" && @@ -246,9 +245,7 @@ done for argv in \ "gc --no-cruft" \ "-c gc.cruftPacks=false gc" \ - "-c gc.cruftPacks=true gc --no-cruft" \ - "-c feature.expiremental=true -c gc.cruftPacks=false gc" \ - "-c feature.experimental=false gc" + "-c gc.cruftPacks=true gc --no-cruft" do test_expect_success "git $argv does not generate a cruft pack" ' test_when_finished "rm -fr repo" &&
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> --- Documentation/config/feature.txt | 3 --- Documentation/config/gc.txt | 2 +- Documentation/git-gc.txt | 5 +++-- Documentation/gitformat-pack.txt | 4 ++-- builtin/gc.c | 6 +----- t/t6500-gc.sh | 9 +++------ 6 files changed, 10 insertions(+), 19 deletions(-)