Hi Maxim,
Maxim Cournoyer <maxim.courno...@gmail.com> skribis:
>>> Attempting a suggested fix by Ludovic in that same conversation [0],
>>> namely, making the snippet field of the <origin> record a thunked one:
>>>
>>> modified guix/packages.scm
>>> @@ -250,7 +250,8 @@ as base32. Otherwise, it must be a bytevector."
>>> (patches origin-patches ; list of file names
>>> (default '()) (delayed))
>>>
>>> - (snippet origin-snippet (default #f)) ; sexp or #f
>>> + (snippet origin-snippet
>>> + (default #f) (thunked)) ; sexp or #f
>>> (patch-flags origin-patch-flags ; list of strings
>>> (default '("-p1")))
>>
>> We should check what this change costs in CPU and memory, but it’s
>> probably worth it. As Marius noted before, the snippets for
>> ungoogled-chromium and linux-libre are contrived because of this
>> limitation. (Perhaps we can use ‘delayed’ instead of ‘thunked’.)
>
> What is the difference between delayed and thunked? Would a thunked
> capture the closure of its environment while delayed not? Is the
> closure useful to access record-bound values such as the version field
> of a package?
‘Thunk’ uses an actual thunk (zero-argument procedure) that’s called
each time the field is accessed; ‘delayed’ uses a promise, which is
similar except that the result is memoized (info "(guile) Delayed
Evaluation").
> I checked the usage at compilation and run time, using the 'time'
> command (aliased to time+ on my system), and didn't find any meaningful
> difference whether the snippet is made a thunked or delayed field, or
> none (current situation):
>
> On current master:
>
> time+ make -j8
> 2436.29user 56.47system 14:29.36elapsed 286%CPU (0avgtext+0avgdata
> 870828maxresident)k
> 5480inputs+405952outputs (71major+320522minor)pagefaults 0swaps
>
> time+ ./pre-inst-env guix package -A | wc -l
> 9.87user 0.24system 0:06.51elapsed 155%CPU (0avgtext+0avgdata
> 281564maxresident)k
> 0inputs+0outputs (0major+25636minor)pagefaults 0swaps
> 14702
What would be interesting is a comparison of the performance of
‘package-derivation’, which can be done with something like:
time guix build -d --no-grafts libreoffice pandoc
For memory consumption, try:
GUIX_PROFILING=gc guix build -d --no-grafts libreoffice pandoc
>> + (snippet
>> + (with-imported-modules '((guix build utils))
>> + #~(begin
>> + (use-modules (guix build utils))
>> + ;; corelib uses bundled harfbuzz, md4, md5, sha3
>> + (with-directory-excursion "src/3rdparty"
>> + (for-each delete-file-recursively
>> + (list "double-conversion" "freetype"
>> "harfbuzz-ng"
>> + "libpng" "libjpeg" "pcre2" "sqlite"
>> "xcb"
>> + "zlib")))
>> +
>> + (let ((coreutils #+(canonical-package coreutils)))
>> + (substitute* "configure"
>> + (("/bin/pwd")
>> + (string-append coreutils "/bin/pwd")))
>> + (substitute* "src/corelib/global/global.pri"
>> + (("/bin/ls")
>> + (string-append coreutils "/bin/ls"))))
>> + #t)))))
>>
>> Such substitutions are system-dependent; thus, they should be made in a
>> phase, not in a snippet. Perhaps we’ll sidestep the issue altogether?
>> :-)
>
> Indeed. I didn't consider this aspect well. Apart from being
> inefficient (the sources of a package would be different for each
> system) it would still technically work, no?
It would work, but it’s “not the right place” for that, aesthetically.
(Note that when there’s a snippet, we get different derivations for each
system anyway.)
Thanks,
Ludo’.
