Subject: Re: [bug#34982] [PATCH] guile-build-system: Support building in parallel.

From: Christopher Baines <[email-masked]>
Date: Sat, 06 Apr 2019 00:50:48 +0100

Ludovic Courtès <[email-masked]> writes:

> Hi,
>
> Christopher Baines <[email-masked]> skribis:
>
>> * guix/build/guile-build-system.scm (build): Use n-par-for-each, instead of
>> for-each, to use multiple cores if available.
>
> [...]
>
>> +    (n-par-for-each
>> +     (parallel-job-count)
>> +     (lambda (file)
>> +       (catch #t
>> +         (lambda ()
>> +           (let* ((go (string-append go-dir
>> +                                     (file-sans-extension file)
>> +                                     ".go")))
>> +             ;; Install source module.
>> +             (install-file (string-append source-directory "/" file)
>> +                           (string-append module-dir
>> +                                          "/" (dirname file)))
>>
>> -                  ;; Install and compile module.
>> -                  (apply invoke guild "compile" "-L" source-directory
>
> It probably doesn’t matter that much, but it feels wrong to create
> threads that do nothing but call ‘waitpid’, essentially.
>
> Commit f07041f7d25badb7d74b8fad6ee446a12af04f63 removed a ‘p-for-each’
> procedure that could be useful here since it directly creates N
> processes and then does (waitpid WAITPID_ANY).  Would it make sense to
> paste it here and use it in lieu of ‘n-par-for-each’?

I've sent a new patch with an updated approach now, I started with the
n-par-for-each procedure, and adapted it. It seems to work, let me know
what you think :)

Chris