Re: [PATCH] Run the bootstrap object comparison in parallel

On 7/21/2026 9:28 AM, [email protected] wrote:
> From: Kyrylo Tkachov <[email protected]>
>
> The stage 2 and stage 3 object comparison runs one command per object in a
> serial shell loop.  Everything after it waits while an otherwise idle machine
> compares thousands of objects.
>
> Generate one make target per object and run the comparisons through $(MAKE),
> so they share the original jobserver.  Keep the generated makefile and result
> shards invocation-specific, clean them on normal and signal exits, and sort
> the shards before creating the traditional .bad_compare diagnostic.  Files in
> the exclusion list still only warn.  Comparator statuses other than zero or
> one now report an operational error instead of being treated as equal.
>
> The tail-based fallback for cmp implementations without byte skipping used
> fixed temporary names.  Give those files process-specific names, clean them
> with a trap, and preserve the same status contract for tail failures and
> signals.
>
> On highly parallel AArch64 and x86_64 systems this reduces comparison wall
> time by about 95%.
>
> ChangeLog:
>
> 	* Makefile.tpl ([+compare-target+]): Run object comparisons through an
> 	invocation-specific parallel sub-make.  Collect sorted failure shards
> 	and clean temporary state on exit.
> 	* Makefile.in: Regenerate.
> 	* configure: Regenerate.
>
> config/ChangeLog:
>
> 	* acx.m4 (ACX_PROG_CMP_IGNORE_INITIAL): Use process-specific temporary
> 	files and clean them on exit.  Diagnose tail failures as errors.
>
> Signed-off-by: Kyrylo Tkachov <[email protected]>
Given the utility of the bootstrap comparison test, I hope you you 
tested with a forced failure to ensure it'll trigger failures properly.

Assuming you've done a force failure test, OK.

jeff