Re: [PATCH 1/2] t4205: compare huge output without diff

From: Patrick Steinhardt <ps@pks.im>
Date: Sep 24, 2026, 06:13 UTC
Message-ID: <arS_l1hPIr7I2Gn-@pks.im>
In-Reply-To: <20260923-ci-large-test-resources-v1-1-c28416d59475@gmail.com>

On Wed, Sep 23, 2026 at 01:13:28PM -0400, Tamir Duberstein wrote:

> The huge-commit test compares two files with a line larger than 2 GiB.
> In Linux GitHub Actions jobs, git log produces its huge output but
> its subsequent diff process is killed with SIGKILL.

I've never seen that failure before. Do you maybe have a link to it?

> Use test_cmp_bin to compare the output byte for byte without constructing
> a line-oriented diff. Remove the two large files after a successful
> comparison, releasing more than 4 GiB before subsequent tests.

It would be great to back up the claim that test_cmp_bin is better than test_cmp, e.g. by comparing peak RSS and its runtime.

Show 17 quoted lines

> Signed-off-by: Tamir Duberstein <tamird@gmail.com>
> ---
>  t/t4205-log-pretty-formats.sh | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
> index 4be5c51489..6279a7e9bc 100755
> --- a/t/t4205-log-pretty-formats.sh
> +++ b/t/t4205-log-pretty-formats.sh
> @@ -1189,7 +1189,8 @@ test_expect_success EXPENSIVE,SIZE_T_IS_64BIT 'set up huge commit' '
>  test_expect_success EXPENSIVE,SIZE_T_IS_64BIT 'log --pretty with huge commit message' '
>  	git log -1 --format="%B%<(1)%x30" $huge_commit >actual &&
>  	echo 0 >>expect &&
> -	test_cmp expect actual
> +	test_cmp_bin expect actual &&
> +	rm expect actual
>  '

Hm. Sure, releasing these files isn't a bad idea by itself. But we rewrite "expect" in the next test anyway, and "actual" will be rewritten two tests further down. So does it really buy us that much...?

Patrick