bug#54495: unexpected download after gc

bug#54495: unexpected download after gc

[zimoun]

Hi,

Considering this with revision a03936a:

    guix gc
    guix install python-ipython -p tools
    guix gc
    guix install python-ipython -p tools

I am surprised that:

 1. the second GC collects things
 2. the second install downloads things

especially by this line:

python-ipython-7.27.0  892KiB  4.6MiB/s 00:00 [##################] 100.0%


Well, it is because of grafts.  The profile contains the grafted
version and the installation expect first the non-grafted for computing
the graft.  For instance:

--8<---------------cut here---------------start------------->8---
$ guix gc --list-dead | grep ipython
finding garbage collector roots...
determining live/dead paths...
/gnu/store/xmw4vxabnkm7vwa0ywfcqcmknbnia0c3-python-ipython-7.27.0

guix build python-ipython --no-grafts
/gnu/store/xmw4vxabnkm7vwa0ywfcqcmknbnia0c3-python-ipython-7.27.0
--8<---------------cut here---------------end--------------->8---

When something is grafted, is it possible to consider the non-grafted as
a "derivation", i.e., control the GC with 'gc-keep-derivations'.

Or the grafted could keep a reference to the non-grafted?


Well, I was expecting that this composition:

    guix gc && guix install

was "idempotent" in a way. :-) And to me, the fact that it is not is
somehow a bug.  Maybe, it is already well-known and not considered as
bug.


Cheers,
simon

bug#54495: unexpected download after gc

[raingloom]

On Fri, 18 Mar 2022 14:50:01 +0100
zimoun <zimon.toutoune@gmail.com> wrote:

> Hi,
> 
> Considering this with revision a03936a:
> 
>     guix gc
>     guix install python-ipython -p tools
>     guix gc
>     guix install python-ipython -p tools
> 
> I am surprised that:
> 
>  1. the second GC collects things
>  2. the second install downloads things
> 
> especially by this line:
> 
> python-ipython-7.27.0  892KiB  4.6MiB/s 00:00 [##################]
> 100.0%
> 
> 
> Well, it is because of grafts.  The profile contains the grafted
> version and the installation expect first the non-grafted for
> computing the graft.  For instance:
> 
> --8<---------------cut here---------------start------------->8---
> $ guix gc --list-dead | grep ipython
> finding garbage collector roots...
> determining live/dead paths...
> /gnu/store/xmw4vxabnkm7vwa0ywfcqcmknbnia0c3-python-ipython-7.27.0
> 
> guix build python-ipython --no-grafts
> /gnu/store/xmw4vxabnkm7vwa0ywfcqcmknbnia0c3-python-ipython-7.27.0
> --8<---------------cut here---------------end--------------->8---
> 
> When something is grafted, is it possible to consider the non-grafted
> as a "derivation", i.e., control the GC with 'gc-keep-derivations'.
> 
> Or the grafted could keep a reference to the non-grafted?
> 
> 
> Well, I was expecting that this composition:
> 
>     guix gc && guix install
> 
> was "idempotent" in a way. :-) And to me, the fact that it is not is
> somehow a bug.  Maybe, it is already well-known and not considered as
> bug.
> 
> 
> Cheers,
> simon
> 
> 
> 

There should definitely be more attention paid to offline use so IMHO
this is a bug. Or at least missing feature.

bug#54495: unexpected download after gc

[David Elsing]

Hello,

AFAICT, there is no way to determine which ungrafted package a grafted
package comes from without the derivation of the grafted package (where
the ungrafted package is referenced). Therefore, I think adding a
reference to the ungrafted package in the package itself (your second
suggestion) would be the simplest way: https://issues.guix.gnu.org/66824

Presently, it is inconvenient to globally run guix gc at all for me, as
many (dependent) packages are deleted and substituted again when
rebuilding several profiles built with grafts.

Cheers,
David

bug#54495: unexpected download after gc

[David Elsing]

Hello,

David Elsing <david.elsing@posteo.net> writes:

> Presently, it is inconvenient to globally run guix gc at all for me, as
> many (dependent) packages are deleted and substituted again when
> rebuilding several profiles built with grafts.

In the meantime, I learned about the '--gc-keep-outputs' and
'--gc-keep-derivations' options for guix-daemon [1], which together
prevent this issue. Of course, this also keeps build dependencies, but
that might be desirable anyway.

Best,
David

[1] https://guix.gnu.org/manual/devel/en/html_node/Invoking-guix_002ddaemon.html