bug#25137: closed (repeated updating list of substitutes during install)

[GNU bug Tracking System]

Your message dated Sun, 29 Mar 2020 15:41:24 +0200
with message-id <address@hidden>
and subject line Re: bug#22990: Grafts leads to inefficient substitute info 
retrieval
has caused the debbugs.gnu.org bug report #22990,
regarding repeated updating list of substitutes during install
to be marked as done.

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-- 
22990: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=22990
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> Subject: 
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> repeated updating list of substitutes during install
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> Date: 
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> Thu, 08 Dec 2016 13:50:07 +0000
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> User-agent: 
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> Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux)
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> During a package install (of guix itself) I see "updating list of
> substitutes" messages repeated through the install, not just at the
> start.  Is that as it should be?  I expected guix to use a recent cached
> version.
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> --- Begin Message ---
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> Subject: 
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> Re: bug#22990: Grafts leads to inefficient substitute info retrieval
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> Date: 
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> Sun, 29 Mar 2020 15:41:24 +0200
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> User-agent: 
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> Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux)
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> Hi younger self!
>
> address@hidden (Ludovic Courtès) skribis:
>
> > As of right now (v0.9.0-2007-g66a30a3), ‘graft-derivation’ works either by:
> >
> >   1. Fetching substitute info about the things being built so that it
> >      can determine its references, which in turns allows it to determine
> >      whether they need to be grafted.
> >
> >   2. Building stuff, as a last resort, so that it can determine its
> >      references.
> >
> > Case #1 is hopefully going to be the most common.
> >
> > The problem with #1 is that when building a profile, we do one
> > ‘package-derivation’ call for each package in the profile, which
> > translates in one ‘graft-derivation’ call for each relevant package¹,
> > which translates into one ‘references/substitutes’ call for each.
> >
> > Concretely, what this means is this:
> >
> >   $ guix package -u
> >   substitute: updating list of substitutes from 'http://mirror.guixsd.org'... 
> > 100.0%
> >   substitute: updating list of substitutes from 'http://mirror.guixsd.org'... 
> > 100.0%
> >   substitute: updating list of substitutes from 'http://mirror.guixsd.org'... 
> > 100.0%
> >   substitute: updating list of substitutes from 'http://mirror.guixsd.org'... 
> > 100.0%
> >   substitute: updating list of substitutes from 'http://mirror.guixsd.org'... 
> > 100.0%
> >   substitute: updating list of substitutes from 'http://mirror.guixsd.org'... 
> > 100.0%
> >   substitute: updating list of substitutes from 'http://mirror.guixsd.org'... 
> > 100.0%
> >   […]
> >   The following files would be downloaded:
> >
> > Each of the initial “updating list” message corresponds to an HTTP
> > request for a single narinfo file, which can take around 1 second.
>
> This is finally fixed with commit
> 710854304b1ab29332edcb76f3de532e0724c197, as discussed earlier this
> week¹.  \o/
>
> The solution is simpler and more orthogonal than what was envisioned
> earlier in this thread, which is nice.
>
> I also potentially addresses other uses of “dynamic dependencies”
> elsewhere in the code base, such as ‘remote-eval’ calls in ‘guix
> deploy’.
>
> Feedback welcome!
>
> Ludo’.
>
> ¹ https://lists.gnu.org/archive/html/guix-devel/2020-03/msg00337.html
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