Excessive temproots size when running guix build

I spotted a problem with data.guix.gnu.org trying to process this old

revision [1]

1: https://data.guix.gnu.org/revision/75dabac633bb9a33efbebf859f8aa4bb3b9582b2

The machine ran out of disk space, as a ~30GiB file had been created in

/var/guix/temproots.

I think I can reproduce the situation by running this command.

guix time-machine --commit=75dabac633bb9a33efbebf859f8aa4bb3b9582b2 -- build --system=armhf-linux guix

It's the build of the guix package that seems to be involved.

For some reason though, I can't reproduce this on my local machine, I

get a build failure for [2].

2: /gnu/store/cz4sr5whzf3qhp8c47bzlfzcxxwl485i-python2-2.7.15.drv

Any ideas? Is there a known issue (perhaps with grafts) for old

revisions of Guix which could lead to excessive temproots file sizes in

some situations?

Hi,

Christopher Baines <mail@cbaines.net> skribis:

Sounds fishy. Those files contain a nul-separated list of GC roots

(store file names). Thus, a file in there is proportional to the number

of ‘add-temp-root’ RPCs made by the client during the session.

A client with a long-running session (‘guix publish’, Coordinator, Data

Service, Cuirass, etc.) that regularly adds temp roots makes that file

grow endlessly.

HTH!

Ludo’.

Ludovic Courtès schreef op ma 06-09-2021 om 23:18 [+0200]:

FWIW, temp roots are added in ‘DerivationGoal::DerivationGoal’

when building things, and ‘DerivationGOal::haveDerivation’,

‘SubstitutionGoal::init’, ‘LocalStore::optimiseStore’

‘LocalStore::addToStoreFromDump’, ‘LocalStore::addTextToStore’,

‘LocalStore::createTempDirInStore’ and ‘LocalStore::importPath’.

I.e., temp roots are not only added from the add-temp-root RPC.

Greetings,

Maxime.