From: Junio C Hamano <gitster@pobox.com>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: "Git List" <git@vger.kernel.org>,
"Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>,
"Michael Haggerty" <mhagger@alum.mit.edu>,
"Stefan Beller" <stefanbeller@gmail.com>,
"Jeff King" <peff@peff.net>,
"Jonathan Nieder" <jrnieder@gmail.com>
Subject: Re: BUG: Race condition due to reflog expiry in "gc"
Date: Wed, 13 Mar 2019 10:43:57 +0900 [thread overview]
Message-ID: <xmqq1s3bh7ky.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <87tvg7brlm.fsf@evledraar.gmail.com> (=?utf-8?B?IsOGdmFyIEFy?= =?utf-8?B?bmZqw7Zyw7A=?= Bjarmason"'s message of "Wed, 13 Mar 2019 00:28:05 +0100")
Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
> I'm still working on fixing a race condition I encountered in "gc"
> recently, but am not 100% sure of the fix. So I thought I'd send a
> braindump of what I have so far in case it jolts any memories.
>
> The problem is that when we "gc" we run "reflog expire --all". This
> iterates over the reflogs, and takes a *.lock for each reference.
>
> It'll fail intermittendly in two ways:
>
> 1. If something is concurrently committing to the repo it'll fail
> because we for a tiny amount of time hold a HEAD.lock file, so HEAD
> can't be updated.
>
> 2. On a repository that's just being "git fetch"'d by some concurrent
> process the "gc" will fail, because the ref's SHA1 has changed,
> which we inspect as we aquire the lock.
Both sounds very much expected and expectable outcome. I am not
sure how they need to be called bugs.
next prev parent reply other threads:[~2019-03-13 1:44 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-12 23:28 BUG: Race condition due to reflog expiry in "gc" Ævar Arnfjörð Bjarmason
2019-03-13 1:43 ` Junio C Hamano [this message]
2019-03-13 10:28 ` Ævar Arnfjörð Bjarmason
2019-03-13 16:02 ` Jeff King
2019-03-13 16:22 ` Ævar Arnfjörð Bjarmason
2019-03-13 23:54 ` [PATCH 0/5] gc: minor code cleanup + contention fixes Ævar Arnfjörð Bjarmason
2019-03-14 12:34 ` [PATCH v2 0/7] " Ævar Arnfjörð Bjarmason
2019-03-15 15:59 ` [PATCH v3 0/8] " Ævar Arnfjörð Bjarmason
2019-03-18 6:13 ` Junio C Hamano
2019-03-28 16:14 ` [PATCH v4 0/7] gc: tests and handle reflog expire config Ævar Arnfjörð Bjarmason
2019-03-28 16:14 ` [PATCH v4 1/7] gc: remove redundant check for gc_auto_threshold Ævar Arnfjörð Bjarmason
2019-03-28 16:14 ` [PATCH v4 2/7] gc: convert to using the_hash_algo Ævar Arnfjörð Bjarmason
2019-03-28 16:14 ` [PATCH v4 3/7] gc: refactor a "call me once" pattern Ævar Arnfjörð Bjarmason
2019-03-28 16:14 ` [PATCH v4 4/7] reflog tests: make use of "test_config" idiom Ævar Arnfjörð Bjarmason
2019-03-28 16:14 ` [PATCH v4 5/7] reflog tests: test for the "points nowhere" warning Ævar Arnfjörð Bjarmason
2019-03-28 16:14 ` [PATCH v4 6/7] reflog tests: assert lack of early exit with expiry="never" Ævar Arnfjörð Bjarmason
2019-03-28 16:14 ` [PATCH v4 7/7] gc: handle & check gc.reflogExpire config Ævar Arnfjörð Bjarmason
2019-03-15 15:59 ` [PATCH v3 1/8] gc: remove redundant check for gc_auto_threshold Ævar Arnfjörð Bjarmason
2019-03-15 15:59 ` [PATCH v3 2/8] gc: convert to using the_hash_algo Ævar Arnfjörð Bjarmason
2019-03-15 15:59 ` [PATCH v3 3/8] gc: refactor a "call me once" pattern Ævar Arnfjörð Bjarmason
2019-03-15 15:59 ` [PATCH v3 4/8] reflog tests: make use of "test_config" idiom Ævar Arnfjörð Bjarmason
2019-03-15 15:59 ` [PATCH v3 5/8] reflog tests: test for the "points nowhere" warning Ævar Arnfjörð Bjarmason
2019-03-15 15:59 ` [PATCH v3 6/8] reflog tests: assert lack of early exit with expiry="never" Ævar Arnfjörð Bjarmason
2019-03-19 6:20 ` Jeff King
2019-03-15 15:59 ` [PATCH v3 7/8] gc: handle & check gc.reflogExpire config Ævar Arnfjörð Bjarmason
2019-03-15 15:59 ` [PATCH v3 8/8] reflog expire: don't assert the OID when locking refs Ævar Arnfjörð Bjarmason
[not found] ` <b870a17d-2103-41b8-3cbc-7389d5fff33a@alum.mit.edu>
2019-03-21 14:10 ` Ævar Arnfjörð Bjarmason
2019-03-19 6:27 ` [PATCH v2 0/7] gc: minor code cleanup + contention fixes Jeff King
2019-03-14 12:34 ` [PATCH v2 1/7] gc: remove redundant check for gc_auto_threshold Ævar Arnfjörð Bjarmason
2019-03-14 12:34 ` [PATCH v2 2/7] gc: convert to using the_hash_algo Ævar Arnfjörð Bjarmason
2019-03-15 9:51 ` Duy Nguyen
2019-03-15 10:42 ` Ævar Arnfjörð Bjarmason
2019-03-15 15:49 ` Johannes Schindelin
2019-03-14 12:34 ` [PATCH v2 3/7] gc: refactor a "call me once" pattern Ævar Arnfjörð Bjarmason
2019-03-14 12:34 ` [PATCH v2 4/7] reflog tests: make use of "test_config" idiom Ævar Arnfjörð Bjarmason
2019-03-14 12:34 ` [PATCH v2 5/7] reflog: exit early if there's no work to do Ævar Arnfjörð Bjarmason
2019-03-15 10:01 ` Duy Nguyen
2019-03-15 15:51 ` Ævar Arnfjörð Bjarmason
2019-03-14 12:34 ` [PATCH v2 6/7] gc: don't run "reflog expire" when keeping reflogs Ævar Arnfjörð Bjarmason
2019-03-15 10:05 ` Duy Nguyen
2019-03-15 10:24 ` Ævar Arnfjörð Bjarmason
2019-03-15 10:32 ` Duy Nguyen
2019-03-15 15:51 ` Johannes Schindelin
2019-03-18 6:04 ` Junio C Hamano
2019-03-14 12:34 ` [PATCH v2 7/7] reflog expire: don't assert the OID when locking refs Ævar Arnfjörð Bjarmason
2019-03-15 11:10 ` Duy Nguyen
2019-03-15 15:52 ` Ævar Arnfjörð Bjarmason
2019-03-13 23:54 ` [PATCH 1/5] gc: remove redundant check for gc_auto_threshold Ævar Arnfjörð Bjarmason
2019-03-14 0:25 ` Jeff King
2019-03-13 23:54 ` [PATCH 2/5] gc: convert to using the_hash_algo Ævar Arnfjörð Bjarmason
2019-03-14 0:26 ` Jeff King
2019-03-13 23:54 ` [PATCH 3/5] gc: refactor a "call me once" pattern Ævar Arnfjörð Bjarmason
2019-03-14 0:30 ` Jeff King
2019-03-13 23:54 ` [PATCH 4/5] gc: don't run "reflog expire" when keeping reflogs Ævar Arnfjörð Bjarmason
2019-03-14 0:40 ` Jeff King
2019-03-14 4:51 ` Junio C Hamano
2019-03-14 19:26 ` Jeff King
2019-03-13 23:54 ` [PATCH 5/5] reflog expire: don't assert the OID when locking refs Ævar Arnfjörð Bjarmason
2019-03-14 0:44 ` Jeff King
2019-03-14 0:25 ` BUG: Race condition due to reflog expiry in "gc" Jeff King
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