Re: Dealing with mass rebuilds

[ludo@gnu.org (Ludovic Courtès)]

Andreas Enge <andreas@enge.fr> skribis:

> On Tue, Oct 20, 2015 at 09:45:54PM +0200, Ludovic Courtès wrote:
>> The Nixpkgs folks have a ‘staging’ branch for changes that cause mass
>> rebuilds but are well tested, such that they can be merged into ‘master’
>> anytime².  Perhaps something we should do as well?
>
> Would that be different from your suggestion that if the curl update caused
> a rebuild of too many packages (whatever that would mean, which is a separate
> discussion) it should not be done on core-updates, but on its own branch,
> for instance, curl-update? One practical advantage I see in  a staging
> branch, if I understand your suggestion correctly, is that one would not need
> to modify the set of jobs on hydra to now also build curl-update, and then
> maybe giflib-update, and then xyz-update, but it would always be called
> "staging".

Yes.

> Now the "well tested" assumption is dubious. I actually do not know whether
> the curl update will go through. I tried to build one of the packages shown
> by "guix refresh -l curl" that looked simple (mpd), but it turned out it
> was not simple at all and needed a lot of rebuilds (including texlive).
> Admittedly, I could have spent more time searching a direct dependency,
> probably by using one of your recent graph drawing commands. So in case
> a problem turns up, would we revert a curl update on the staging branch
> and do more local work before proposing it again?

Ideally, we’d test as much as possible locally, or, for important
library updates, in a dedicated branch.

The TeX Live issue is orthogonal: We seriously need a ‘texlive-minimal’
variant, and the full-blown ‘texlive’ must not be depended on by any
other package.

> And if Efraim wished to do a gitlib update after my curl update, what would
> be the protocol? Would he be expected to wait until the hydra build of the
> curl update has finished? Or at least until it has finished on x86_64?
> Otherwise, we would again face the risk of the staging branch becoming
> an update-the-world branch with unforeseen ramifications.

Yeah, for sure.  I have to admit that we may be unable to do much better
until we can finally change the hydra.gnu.org front-end, which is the
main bottleneck here (at least for i686/x86_64.)

Thanks,
Ludo’.