> On Mon, Oct 31 2022, Mark Hills wrote: > > > On Mon, 31 Oct 2022, Ævar Arnfjörð Bjarmason wrote: > > > >> > >> On Mon, Oct 31 2022, Mark Hills wrote: > >> > >> > Our use case: we commit some compiled objects to the repo, where compiling > >> > is either slow or requires software which is not always available. > >> > > >> > Since upgrading Git 2.26.3 -> 2.32.4 (as part of Alpine Linux OS upgrade) > >> > we are noticing a change in build behaviour. > >> > > >> > Now, after a "git clone" we find the Makefile intermittently attempting > >> > (and failing) some builds that are not intended. > >> > > >> > Indeed, Make is acting reasonably as the source file is sometimes > >> > marginally newer than the destination (both checked out by Git), example > >> > below. > >> > > >> > I've never had to consider consistency timestamps within a Git checkout > >> > until now. > >> > > >> > It's entirely possible there's _never_ a guarantee of consistency here. > >> > > >> > But then something has certainly changed in practice, as this fault has > >> > gone from never happening to now every couple of days. > >> > > >> > Imaginging I can't be the first person to encounter this, I searched for > >> > existing threads or docs, but overwhemingly the results were question of > >> > Git tracking the timestamps (as part of the commit) which this is not; > >> > it's consistency within one checkout. > >> > > >> > $ git clone --depth 1 file:///path/to/repo.git > >> > > >> > $ stat winner.jpeg > >> > File: winner.jpeg > >> > Size: 258243 Blocks: 520 IO Block: 4096 regular file > >> > Device: fd07h/64775d Inode: 33696 Links: 1 > >> > Access: (0644/-rw-r--r--) Uid: ( 106/ luthier) Gid: ( 106/ luthier) > >> > Access: 2022-10-31 16:05:17.756858496 +0000 > >> > Modify: 2022-10-31 16:05:17.756858496 +0000 > >> > Change: 2022-10-31 16:05:17.756858496 +0000 > >> > Birth: - > >> > > >> > $ stat winner.svg > >> > File: winner.svg > >> > Size: 52685 Blocks: 112 IO Block: 4096 regular file > >> > Device: fd07h/64775d Inode: 33697 Links: 1 > >> > Access: (0644/-rw-r--r--) Uid: ( 106/ luthier) Gid: ( 106/ luthier) > >> > Access: 2022-10-31 16:05:17.766859030 +0000 > >> > Modify: 2022-10-31 16:05:17.766859030 +0000 > >> > Change: 2022-10-31 16:05:17.766859030 +0000 > >> > Birth: - > >> > > >> > Elsewhere in the repository, it's clear the timestamps are not consistent: > >> > > >> > $ stat Makefile > >> > File: Makefile > >> > Size: 8369 Blocks: 24 IO Block: 4096 regular file > >> > Device: fd07h/64775d Inode: 33655 Links: 1 > >> > Access: (0644/-rw-r--r--) Uid: ( 106/ luthier) Gid: ( 106/ luthier) > >> > Access: 2022-10-31 16:05:51.628660212 +0000 > >> > Modify: 2022-10-31 16:05:17.746857963 +0000 > >> > Change: 2022-10-31 16:05:17.746857963 +0000 > >> > Birth: - > >> > >> I think you're almost certainly running into the parallel checkout, > >> which is new in that revision range. Try tweaking checkout.workers and > >> checkout.thresholdForParallelism (see "man git-config"). This does look like something you would see with parallel checkout, yes. But... > > Thanks, it will be interesting to try this and I'll report back. > > FWIW I was under the impression that we'd made it the default, so unless > you opted-in it's probably not that. ... it indeed should be disabled by default. It seems Mark didn't manually enable parallel checkout, as the original message only mentions the git upgrade as a changing factor. And Alpine's git installation script for 2.32.4 [1] doesn't seem to change our defaults either. Perhaps, it just happens that 2.32.4 changed the checkout processing time slightly so that each entry is finished a bit slower (or the system was overloaded at that moment?). Anyways, the creation order (based on the mtimes) looks correct to me from a sequential-checkout point of view: first Makefile, than winner.jpeg, and finally winner.svg. That's the order in which these files would appear in the index, which is the order followed by sequential checkout. [1]: https://git.alpinelinux.org/aports/tree/main/git/APKBUILD?h=3.14-stable&id=0f3285f2cfcb8362460002c27e219fadbf18c885
