From: Junio C Hamano <gitster@pobox.com>
To: "Elijah Newren via GitGitGadget" <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, Elijah Newren <newren@gmail.com>
Subject: Re: [PATCH] t6022, t6046: fix flaky files-are-updated checks
Date: Fri, 13 Mar 2020 12:18:24 -0700 [thread overview]
Message-ID: <xmqqtv2sawsf.fsf@gitster.c.googlers.com> (raw)
In-Reply-To: <pull.725.git.git.1584125875550.gitgitgadget@gmail.com> (Elijah Newren via GitGitGadget's message of "Fri, 13 Mar 2020 18:57:55 +0000")
"Elijah Newren via GitGitGadget" <gitgitgadget@gmail.com> writes:
> From: Elijah Newren <newren@gmail.com>
>
> Several tests wanted to verify that files were actually modified by a
> merge, which it would do by checking that the mtime was updated. In
> order to avoid problems with the merge completing so fast that the mtime
> at the beginning and end of the operation was the same, these tests
> would first set the mtime of a file to something "old". This "old"
> value was usually determined as current system clock minus one second,
> truncated to the nearest integer. Unfortunately, it appears the system
> clock and filesystem clock are different and comparing across the two
> runs into race problems resulting in flaky tests.
Good observation (and if we were doing networked filesystems, things
would be worse).
> So, instead of trying to compare across what are effectively two
> different clocks, just avoid using the system clock. Any new updates to
> files have to give an mtime at least as big as what is already in the
> file, so define "old" as one second before the mtime found in the file
> before the merge starts.
Is there a reason why we prefer as small an offset as possible? I
am not objecting to the choice of 1 second, but am curious if
anything bad happens if we used a larger offset, say, 2 hours.
Thanks.
next prev parent reply other threads:[~2020-03-13 19:18 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-13 18:57 [PATCH] t6022, t6046: fix flaky files-are-updated checks Elijah Newren via GitGitGadget
2020-03-13 19:18 ` Junio C Hamano [this message]
2020-03-13 19:27 ` Elijah Newren
2020-03-13 19:42 ` Junio C Hamano
2020-03-13 20:03 ` [PATCH v2] " Elijah Newren via GitGitGadget
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