Re: Drastic jump in the time required for the test suite

From: Stefan Beller <sbeller@google.com>
Date: Oct 20, 2016, 21:53 UTC
Message-ID: <CAGZ79kZkSwbiYD=G_nSZW8_qeb2q+AOsqYipmEigTN1aNYPiEw@mail.gmail.com>
In-Reply-To: <20161020213803.7d7bymby7pouzij3@sigill.intra.peff.net>

On Thu, Oct 20, 2016 at 2:38 PM, Jeff King <peff@peff.net> wrote:

Show 22 quoted lines

> On Thu, Oct 20, 2016 at 12:54:32PM -0700, Stefan Beller wrote:
>
>> Maybe we should stop introducing un-optimized tests.
>> [...]
>> * heavy use of the "git -C <dir>" pattern. When applying that
>>   thouroughly we'd save spanning the subshells.
>
> Yeah, I imagine with some style changes we could drop quite a few
> subshells. The problem is that the conversion work is manual and
> tedious. I'd look first for spots where we can eliminate thousands of
> calls with a single change.
>
>> That said I really like the idea of having a helper that would eliminate the cat
>> for you, e.g. :
>>
>> git_test_helper_equal_stdin_or_diff_and_die -C super_repo status
>> --porcelain=v2 --branch --untracked-files=all <<-EOF
>> 1 A. N... 000000 100644 100644 $_z40 $HMOD .gitmodules
>> 1 AM S.M. 000000 160000 160000 $_z40 $HSUP sub1
>> EOF
>
> I think that helper still ends up using "cat" and "diff" under the hood,

I assumed that helper being a C program, that only needs to fork once for the actual git call and then it sits idle to compare the exact output from stdout to its stdin.

If there is a difference it will do the extra work (i.e. put stdin and stout to a file and call diff on it)