Subject: Re: [PATCH 2/2] tests: introduce --stress-jobs=<N>

From: SZEDER Gábor <[email-masked]>
Date: Sun, 3 Mar 2019 15:19:46 +0100

On Sat, Mar 02, 2019 at 01:19:44PM -0800, Johannes Schindelin via GitGitGadget wrote:
> The --stress option currently accepts an argument, but it is confusing
> to at least this user that the argument does not define the maximal
> number of stress iterations, but instead the number of jobs to run in
> parallel per stress iteration.

Well, these options' description in 't/README' is quite clear on what
they do.  If the lack of updates to 't/README' in these patches is any
indication, then you haven't read that :) but doing so might very well
have avoided your confusion in the first place.

According to my Bash history, I used '--stress=<even-more-cpu-cores>'
about 20x more often than '--stress-limit=<N>'.  That's not surprising
at all, since the main point is to try to trigger rare, hard to
reproduce failures, no matter how many repetitions it takes.  And even
if there is an upper bound, it is usually not the number of
repetitions I know in advance, but rather the time I'm willing to
sacrifice on it, e.g. how long I'm on lunch break or doing groceries,
or when I need my CPUs for more important things, or simply when I
give up, and hit ctrl-C.

And with --stress-jobs=<N> I will have to type more :)

> Let's introduce a separate option for that, whose name makes it more
> obvious what it is about, and let --stress=<N> error out with a helpful
> suggestion about the two options tha could possibly have been meant.
> 
> Signed-off-by: Johannes Schindelin <[email-masked]>
> ---
>  t/test-lib.sh | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/t/test-lib.sh b/t/test-lib.sh
> index ab7f27ec6a..6e557982a2 100644
> --- a/t/test-lib.sh
> +++ b/t/test-lib.sh
> @@ -142,10 +142,16 @@ do
>  	--stress)
>  		stress=t ;;
>  	--stress=*)
> +		echo "error: --stress does not accept an argument: '$opt'" >&2
> +		echo "did you mean --stress-jobs=${opt#*=} or --stress-limit=${opt#*=}?" >&2
> +		exit 1
> +		;;
> +	--stress-jobs=*)
> +		stress=t;
>  		stress=${opt#--*=}
>  		case "$stress" in
>  		*[!0-9]*|0*|"")
> -			echo "error: --stress=<N> requires the number of jobs to run" >&2
> +			echo "error: --stress-jobs=<N> requires the number of jobs to run" >&2
>  			exit 1
>  			;;
>  		*)	# Good.
> -- 
> gitgitgadget