From: Jeff King <peff@peff.net>
To: Neeraj Singh via GitGitGadget <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, Neeraj-Personal <nksingh85@gmail.com>,
"Johannes Schindelin" <Johannes.Schindelin@gmx.de>,
"Jeff Hostetler" <jeffhost@microsoft.com>,
"Christoph Hellwig" <hch@lst.de>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
"Randall S. Becker" <rsbecker@nexbridge.com>,
"Bagas Sanjaya" <bagasdotme@gmail.com>,
"Neeraj K. Singh" <neerajsi@microsoft.com>
Subject: Re: [PATCH v7 1/9] object-file.c: do not rename in a temp odb
Date: Tue, 28 Sep 2021 19:55:54 -0400 [thread overview]
Message-ID: <YVOrikAl/u5/Vi61@coredump.intra.peff.net> (raw)
In-Reply-To: <6e65f68fd6d4d90b0a7bca2e2e57ace9ad749266.1632871971.git.gitgitgadget@gmail.com>
On Tue, Sep 28, 2021 at 11:32:43PM +0000, Neeraj Singh via GitGitGadget wrote:
> If a temporary ODB is active, as determined by GIT_QUARANTINE_PATH
> being set, create object files with their final names. This avoids
> an extra rename beyond what is needed to merge the temporary ODB in
> tmp_objdir_migrate.
What's our goal here? Is it the performance of avoiding the extra
rename()? Or do we benefit from the simplicity of avoiding it?
If the former, do we have measurements on how much this matters?
If the latter, what does the simplicity buy us? I thought maybe it would
make reasoning about fsync() easier, because we don't have to worry
about fsyncing the rename. But we'd eventually have to rename() into the
real object directory anyway.
The reason I want to push back is...
> Creating an object file with the expected final name should be okay
> since the git process writing to the temporary object store is the
> only writer, and it only invokes write_loose_object/create_object_file
> after checking that the object doesn't exist.
...this seems like a kind-of dangerous assumption. Most of the time,
yeah, I'd expect just a single process to be writing. But one of the
things that happens during the receive-pack quarantine is that we run
hooks, which can run any set of arbitrary Git commands, including
simultaneous readers and writers. It seems like we might be introducing
subtle races there.
-Peff
next prev parent reply other threads:[~2021-09-28 23:56 UTC|newest]
Thread overview: 160+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-25 1:51 [PATCH 0/2] [RFC] Implement a bulk-checkin option for core.fsyncObjectFiles Neeraj K. Singh via GitGitGadget
2021-08-25 1:51 ` [PATCH 1/2] object-file: use futimes rather than utime Neeraj Singh via GitGitGadget
2021-08-25 13:51 ` Johannes Schindelin
2021-08-25 22:08 ` Neeraj Singh
2021-08-25 1:51 ` [PATCH 2/2] core.fsyncobjectfiles: batch disk flushes Neeraj Singh via GitGitGadget
2021-08-25 5:38 ` Christoph Hellwig
2021-08-25 17:40 ` Neeraj Singh
2021-08-26 5:54 ` Christoph Hellwig
2021-08-25 16:11 ` Ævar Arnfjörð Bjarmason
2021-08-26 0:49 ` Neeraj Singh
2021-08-26 5:50 ` Christoph Hellwig
2021-08-28 0:20 ` Neeraj Singh
2021-08-28 6:57 ` Christoph Hellwig
2021-08-31 19:59 ` Neeraj Singh
2021-09-01 5:09 ` Christoph Hellwig
2021-08-26 5:57 ` Christoph Hellwig
2021-08-25 18:52 ` Johannes Schindelin
2021-08-25 21:26 ` Junio C Hamano
2021-08-26 1:19 ` Neeraj Singh
2021-08-25 16:58 ` [PATCH 0/2] [RFC] Implement a bulk-checkin option for core.fsyncObjectFiles Neeraj Singh
2021-08-27 23:49 ` [PATCH v2 0/6] Implement a batched fsync " Neeraj K. Singh via GitGitGadget
2021-08-27 23:49 ` [PATCH v2 1/6] object-file: use futimens rather than utime Neeraj Singh via GitGitGadget
2021-08-27 23:49 ` [PATCH v2 2/6] bulk-checkin: rename 'state' variable and separate 'plugged' boolean Neeraj Singh via GitGitGadget
2021-08-27 23:49 ` [PATCH v2 3/6] core.fsyncobjectfiles: batched disk flushes Neeraj Singh via GitGitGadget
2021-08-27 23:49 ` [PATCH v2 4/6] core.fsyncobjectfiles: add windows support for batch mode Neeraj Singh via GitGitGadget
2021-08-27 23:49 ` [PATCH v2 5/6] update-index: use the bulk-checkin infrastructure Neeraj Singh via GitGitGadget
2021-08-27 23:49 ` [PATCH v2 6/6] core.fsyncobjectfiles: performance tests for add and stash Neeraj Singh via GitGitGadget
2021-09-07 19:44 ` [PATCH v2 0/6] Implement a batched fsync option for core.fsyncObjectFiles Neeraj Singh
2021-09-07 19:50 ` Ævar Arnfjörð Bjarmason
2021-09-07 19:54 ` Randall S. Becker
2021-09-08 0:54 ` Neeraj Singh
2021-09-08 1:22 ` Ævar Arnfjörð Bjarmason
2021-09-08 14:04 ` Randall S. Becker
2021-09-08 19:01 ` Neeraj Singh
2021-09-08 0:55 ` Neeraj Singh
2021-09-08 6:44 ` Junio C Hamano
2021-09-08 6:49 ` Christoph Hellwig
2021-09-08 13:57 ` Randall S. Becker
2021-09-08 14:13 ` 'Christoph Hellwig'
2021-09-08 14:25 ` Randall S. Becker
2021-09-08 16:34 ` Neeraj Singh
2021-09-08 19:12 ` Junio C Hamano
2021-09-08 19:20 ` Neeraj Singh
2021-09-08 19:23 ` Ævar Arnfjörð Bjarmason
2021-09-14 3:38 ` [PATCH v3 " Neeraj K. Singh via GitGitGadget
2021-09-14 3:38 ` [PATCH v3 1/6] bulk-checkin: rename 'state' variable and separate 'plugged' boolean Neeraj Singh via GitGitGadget
2021-09-14 3:38 ` [PATCH v3 2/6] core.fsyncobjectfiles: batched disk flushes Neeraj Singh via GitGitGadget
2021-09-14 10:39 ` Bagas Sanjaya
2021-09-14 19:05 ` Neeraj Singh
2021-09-14 19:34 ` Junio C Hamano
2021-09-14 20:33 ` Junio C Hamano
2021-09-15 4:55 ` Neeraj Singh
2021-09-14 3:38 ` [PATCH v3 3/6] core.fsyncobjectfiles: add windows support for batch mode Neeraj Singh via GitGitGadget
2021-09-14 3:38 ` [PATCH v3 4/6] update-index: use the bulk-checkin infrastructure Neeraj Singh via GitGitGadget
2021-09-14 19:35 ` Junio C Hamano
2021-09-14 3:38 ` [PATCH v3 5/6] core.fsyncobjectfiles: performance tests for add and stash Neeraj Singh via GitGitGadget
2021-09-14 3:38 ` [PATCH v3 6/6] core.fsyncobjectfiles: enable batch mode for testing Neeraj Singh via GitGitGadget
2021-09-15 16:21 ` Junio C Hamano
2021-09-15 22:43 ` Neeraj Singh
2021-09-15 23:12 ` Junio C Hamano
2021-09-16 6:19 ` Junio C Hamano
2021-09-14 5:49 ` [PATCH v3 0/6] Implement a batched fsync option for core.fsyncObjectFiles Christoph Hellwig
2021-09-20 22:15 ` [PATCH v4 " Neeraj K. Singh via GitGitGadget
2021-09-20 22:15 ` [PATCH v4 1/6] bulk-checkin: rename 'state' variable and separate 'plugged' boolean Neeraj Singh via GitGitGadget
2021-09-20 22:15 ` [PATCH v4 2/6] core.fsyncobjectfiles: batched disk flushes Neeraj Singh via GitGitGadget
2021-09-21 23:16 ` Ævar Arnfjörð Bjarmason
2021-09-22 1:23 ` Neeraj Singh
2021-09-22 2:02 ` Ævar Arnfjörð Bjarmason
2021-09-22 19:46 ` Neeraj Singh
2021-09-20 22:15 ` [PATCH v4 3/6] core.fsyncobjectfiles: add windows support for batch mode Neeraj Singh via GitGitGadget
2021-09-21 23:42 ` Ævar Arnfjörð Bjarmason
2021-09-22 1:23 ` Neeraj Singh
2021-09-20 22:15 ` [PATCH v4 4/6] update-index: use the bulk-checkin infrastructure Neeraj Singh via GitGitGadget
2021-09-21 23:46 ` Ævar Arnfjörð Bjarmason
2021-09-22 1:27 ` Neeraj Singh
2021-09-23 22:32 ` Neeraj Singh
2021-09-20 22:15 ` [PATCH v4 5/6] core.fsyncobjectfiles: tests for batch mode Neeraj Singh via GitGitGadget
2021-09-21 23:54 ` Ævar Arnfjörð Bjarmason
2021-09-22 1:30 ` Neeraj Singh
2021-09-22 1:58 ` Ævar Arnfjörð Bjarmason
2021-09-22 17:55 ` Neeraj Singh
2021-09-22 20:01 ` Ævar Arnfjörð Bjarmason
2021-09-20 22:15 ` [PATCH v4 6/6] core.fsyncobjectfiles: performance tests for add and stash Neeraj Singh via GitGitGadget
2021-09-24 20:12 ` [PATCH v5 0/7] Implement a batched fsync option for core.fsyncObjectFiles Neeraj K. Singh via GitGitGadget
2021-09-24 20:12 ` [PATCH v5 1/7] object-file.c: do not rename in a temp odb Neeraj Singh via GitGitGadget
2021-09-24 20:12 ` [PATCH v5 2/7] bulk-checkin: rename 'state' variable and separate 'plugged' boolean Neeraj Singh via GitGitGadget
2021-09-24 20:12 ` [PATCH v5 3/7] core.fsyncobjectfiles: batched disk flushes Neeraj Singh via GitGitGadget
2021-09-24 21:47 ` Neeraj Singh
2021-09-24 20:12 ` [PATCH v5 4/7] update-index: use the bulk-checkin infrastructure Neeraj Singh via GitGitGadget
2021-09-24 21:49 ` Neeraj Singh
2021-09-24 20:12 ` [PATCH v5 5/7] unpack-objects: " Neeraj Singh via GitGitGadget
2021-09-24 20:12 ` [PATCH v5 6/7] core.fsyncobjectfiles: tests for batch mode Neeraj Singh via GitGitGadget
2021-09-24 20:12 ` [PATCH v5 7/7] core.fsyncobjectfiles: performance tests for add and stash Neeraj Singh via GitGitGadget
2021-09-24 23:31 ` [PATCH v5 0/7] Implement a batched fsync option for core.fsyncObjectFiles Neeraj Singh
2021-09-24 23:53 ` [PATCH v6 0/8] " Neeraj K. Singh via GitGitGadget
2021-09-24 23:53 ` [PATCH v6 1/8] object-file.c: do not rename in a temp odb Neeraj Singh via GitGitGadget
2021-09-24 23:53 ` [PATCH v6 2/8] bulk-checkin: rename 'state' variable and separate 'plugged' boolean Neeraj Singh via GitGitGadget
2021-09-24 23:53 ` [PATCH v6 3/8] core.fsyncobjectfiles: batched disk flushes Neeraj Singh via GitGitGadget
2021-09-25 3:15 ` Bagas Sanjaya
2021-09-27 0:27 ` Neeraj Singh
2021-09-24 23:53 ` [PATCH v6 4/8] core.fsyncobjectfiles: add windows support for batch mode Neeraj Singh via GitGitGadget
2021-09-27 20:07 ` Junio C Hamano
2021-09-27 20:55 ` Neeraj Singh
2021-09-27 21:03 ` Neeraj Singh
2021-09-27 23:53 ` Junio C Hamano
2021-09-24 23:53 ` [PATCH v6 5/8] update-index: use the bulk-checkin infrastructure Neeraj Singh via GitGitGadget
2021-09-24 23:53 ` [PATCH v6 6/8] unpack-objects: " Neeraj Singh via GitGitGadget
2021-09-24 23:53 ` [PATCH v6 7/8] core.fsyncobjectfiles: tests for batch mode Neeraj Singh via GitGitGadget
2021-09-24 23:53 ` [PATCH v6 8/8] core.fsyncobjectfiles: performance tests for add and stash Neeraj Singh via GitGitGadget
2021-09-28 23:32 ` [PATCH v7 0/9] Implement a batched fsync option for core.fsyncObjectFiles Neeraj K. Singh via GitGitGadget
2021-09-28 23:32 ` [PATCH v7 1/9] object-file.c: do not rename in a temp odb Neeraj Singh via GitGitGadget
2021-09-28 23:55 ` Jeff King [this message]
2021-09-29 0:10 ` Neeraj Singh
2021-09-28 23:32 ` [PATCH v7 2/9] tmp-objdir: new API for creating temporary writable databases Neeraj Singh via GitGitGadget
2021-09-29 8:41 ` Elijah Newren
2021-09-29 16:40 ` Neeraj Singh
2021-09-28 23:32 ` [PATCH v7 3/9] bulk-checkin: rename 'state' variable and separate 'plugged' boolean Neeraj Singh via GitGitGadget
2021-09-28 23:32 ` [PATCH v7 4/9] core.fsyncobjectfiles: batched disk flushes Neeraj Singh via GitGitGadget
2021-09-28 23:32 ` [PATCH v7 5/9] core.fsyncobjectfiles: add windows support for batch mode Neeraj Singh via GitGitGadget
2021-09-28 23:32 ` [PATCH v7 6/9] update-index: use the bulk-checkin infrastructure Neeraj Singh via GitGitGadget
2021-09-28 23:32 ` [PATCH v7 7/9] unpack-objects: " Neeraj Singh via GitGitGadget
2021-09-28 23:32 ` [PATCH v7 8/9] core.fsyncobjectfiles: tests for batch mode Neeraj Singh via GitGitGadget
2021-09-28 23:32 ` [PATCH v7 9/9] core.fsyncobjectfiles: performance tests for add and stash Neeraj Singh via GitGitGadget
2021-10-04 16:57 ` [PATCH v8 0/9] Implement a batched fsync option for core.fsyncObjectFiles Neeraj K. Singh via GitGitGadget
2021-10-04 16:57 ` [PATCH v8 1/9] tmp-objdir: new API for creating temporary writable databases Neeraj Singh via GitGitGadget
2021-10-04 16:57 ` [PATCH v8 2/9] tmp-objdir: disable ref updates when replacing the primary odb Neeraj Singh via GitGitGadget
2021-10-04 16:57 ` [PATCH v8 3/9] bulk-checkin: rename 'state' variable and separate 'plugged' boolean Neeraj Singh via GitGitGadget
2021-10-04 16:57 ` [PATCH v8 4/9] core.fsyncobjectfiles: batched disk flushes Neeraj Singh via GitGitGadget
2021-10-04 16:57 ` [PATCH v8 5/9] core.fsyncobjectfiles: add windows support for batch mode Neeraj Singh via GitGitGadget
2021-10-04 16:57 ` [PATCH v8 6/9] update-index: use the bulk-checkin infrastructure Neeraj Singh via GitGitGadget
2021-10-04 16:57 ` [PATCH v8 7/9] unpack-objects: " Neeraj Singh via GitGitGadget
2021-10-04 16:57 ` [PATCH v8 8/9] core.fsyncobjectfiles: tests for batch mode Neeraj Singh via GitGitGadget
2021-10-04 16:57 ` [PATCH v8 9/9] core.fsyncobjectfiles: performance tests for add and stash Neeraj Singh via GitGitGadget
2021-11-15 23:50 ` [PATCH v9 0/9] Implement a batched fsync option for core.fsyncObjectFiles Neeraj K. Singh via GitGitGadget
2021-11-15 23:50 ` [PATCH v9 1/9] tmp-objdir: new API for creating temporary writable databases Neeraj Singh via GitGitGadget
2021-11-30 21:27 ` Elijah Newren
2021-11-30 21:52 ` Neeraj Singh
2021-11-30 22:36 ` Elijah Newren
2021-11-15 23:50 ` [PATCH v9 2/9] tmp-objdir: disable ref updates when replacing the primary odb Neeraj Singh via GitGitGadget
2021-11-16 7:23 ` Ævar Arnfjörð Bjarmason
2021-11-16 20:38 ` Neeraj Singh
2021-11-15 23:50 ` [PATCH v9 3/9] bulk-checkin: rename 'state' variable and separate 'plugged' boolean Neeraj Singh via GitGitGadget
2021-11-15 23:50 ` [PATCH v9 4/9] core.fsyncobjectfiles: batched disk flushes Neeraj Singh via GitGitGadget
2021-11-15 23:50 ` [PATCH v9 5/9] core.fsyncobjectfiles: add windows support for batch mode Neeraj Singh via GitGitGadget
2021-11-15 23:51 ` [PATCH v9 6/9] update-index: use the bulk-checkin infrastructure Neeraj Singh via GitGitGadget
2021-11-15 23:51 ` [PATCH v9 7/9] unpack-objects: " Neeraj Singh via GitGitGadget
2021-11-15 23:51 ` [PATCH v9 8/9] core.fsyncobjectfiles: tests for batch mode Neeraj Singh via GitGitGadget
2021-11-15 23:51 ` [PATCH v9 9/9] core.fsyncobjectfiles: performance tests for add and stash Neeraj Singh via GitGitGadget
2021-11-16 8:02 ` [PATCH v9 0/9] Implement a batched fsync option for core.fsyncObjectFiles Ævar Arnfjörð Bjarmason
2021-11-17 7:06 ` Neeraj Singh
2021-11-17 7:24 ` Ævar Arnfjörð Bjarmason
2021-11-18 5:03 ` Neeraj Singh
2021-12-01 14:15 ` Ævar Arnfjörð Bjarmason
2022-03-09 23:02 ` Ævar Arnfjörð Bjarmason
2022-03-10 1:16 ` Neeraj Singh
2022-03-10 14:01 ` Ævar Arnfjörð Bjarmason
2022-03-10 17:52 ` Neeraj Singh
2022-03-10 18:08 ` rsbecker
2022-03-10 18:43 ` Neeraj Singh
2022-03-10 18:48 ` rsbecker
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