Re: main != master at github.com/git/git

From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Junio C Hamano <gitster@pobox.com>
Cc: rsbecker@nexbridge.com, 'Jeff King' <peff@peff.net>,
	'Taylor Blau' <me@ttaylorr.com>,
	'Andy Koppe' <andy.koppe@gmail.com>,
	git@vger.kernel.org
Subject: Re: main != master at github.com/git/git
Date: Mon, 21 Aug 2023 16:56:28 +0200 (CEST)	[thread overview]
Message-ID: <15b89f2e-adb8-ea2b-fd74-2cbe95e20501@gmx.de> (raw)
In-Reply-To: <xmqqo7j5uqza.fsf@gitster.g>

Hi Junio,

On Thu, 17 Aug 2023, Junio C Hamano wrote:

> <rsbecker@nexbridge.com> writes:
>
> [...] when CI runner sees branches updated to commit that hasn't been
> worked on, a new job is created to work on that commit, and updating two
> branches with the same commit at the same time unfortunately means two
> independent CI jobs work on the same commit in parallel.

My understanding is that the recommended way to handle this via the
`concurrency` key [*1*]. That is, if we changed

    concurrency:
      group: windows-build-${{ github.ref }}
      cancel-in-progress: ${{ needs.ci-config.outputs.skip_concurrent == 'yes' }}

to

    concurrency:
      group: windows-build-${{ github.sha }}

then pushing both `master` and `next` pointing at the same commit would
start only one of the workflow runs immediately, keeping the second one
pending until the first run is done. If the first run succeeds, the second
run will pick up that status and avoid running everything all over again,
via `skip-if-redundant`.

Ciao,
Johannes

Footnote *1*:
https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#concurrency