# Re: \[PATCH 2/3\] t: add "test-tool genbytes" to avoid slow tr(1) on macOS

- From: Johannes Sixt \<hidden\>
- Date: 2026-11-08 08:54:34 
- List: git
- Page: https://ratatoskr.run/git/2026/11/17891785
- Thread: https://ratatoskr.run/git/2026/11/17888358/t.md

```text
Am 07.11.26 um 15:59 schrieb Kristofer Karlsson via GitGitGadget:
> Several tests create fixture data consisting of a single repeated
> character with "test-tool genzeros <count> | tr '\000' <char>".  This
> works well on platforms where tr(1) is implemented efficiently.
> 
> The implementation of tr(1) on macOS supports multi-byte characters,
> and processes its input one character at a time through
> getwchar() and putwchar(), even in the C locale.  For small inputs
> that does not matter, but t4205 generates more than 2GB of data this
> way, which makes that test much slower on macOS than on Linux: on the
> macOS CI runners, tr(1) alone spends 95 to 123 seconds of CPU time on
> it, compared to about 6 seconds on Linux.
> 
> Fix this by adding "test-tool genbytes <byte> [<count>]", which writes
> the requested byte directly, and turn "genzeros" into a thin
> wrapper around the same code.

All cases that do not need a particular character can use

	printf %0.500d 0

Though, on my Linux box,

	printf %0.2147483649d 0

produces nothing, but

	printf 000000000%0.2147483640d 0

has 2147483649 bytes of output.

If this isn't insanely slow on macOS, use this pattern instead of a
highly engineered helper program? ;-)

-- Hannes

```