Howdy Ricardo,

Ricardo Wurmus <rekado@elephly.net> skribis:

>> Unfortunately, this is not fully deterministic: when running --check
>> several times in a row, I occasionally get different results.  I suspect
>> GDBM’s output is not fully deterministic.
>
> Hmm, I dumped the contents of the generated databases with gdbm_dump and
> couldn’t find any difference aside from the header (which is produced by
> gdbm_dump itself).  Diffoscope shows a lot of differences, though.
>
> I thought that maybe the difference comes from the fact that upon adding
> new entries gdbm grows the hash table.  After setting the initial size
> to a multiple of the number of entries I haven’t been able to generate a
> non-reproducible database.
>
> My only change is in “write-mandb-database”:
>
>   (gdbm-open file GDBM_WRCREAT #:block-size (* 512 (length entries)))
>
> I tried this:
>
>     ./pre-inst-env guix package -p foo -i coreutils guile
>     for i in `seq 30`; do ./pre-inst-env guix build --check -K /gnu/store/pg3684khpj69py40v7p76b90r9q4j2lv-manual-database.drv; done
>
> Seems fine.  Coincidence or did I get lucky?

I checked with the program below.  It helps, but does not entirely fix
it: