Subject: bug#26225: [PATCH] guix: Compress and decompress xz archives in parallel.

From: Marius Bakke <[email-masked]>
Date: Sat, 01 Apr 2017 08:52:28 +0200

Leo Famulari <[email-masked]> writes:

> Efraim Flashner wrote:
>> * guix/scripts/pack.scm (%compressors): Add flag '-T0' when calling "xz".
>> * guix/utils.scm (decompressed-port, compressed-port,
>> compressed-output-port): Same.
>
>> --- a/guix/utils.scm
>> +++ b/guix/utils.scm
>> @@ -154,7 +155,7 @@ a symbol such as 'xz."
>>    (match compression
>>      ((or #f 'none) (values input '()))
>>      ('bzip2        (filtered-port `(,%bzip2 "-dc") input))
>> -    ('xz           (filtered-port `(,%xz "-dc") input))
>> +    ('xz           (filtered-port `(,%xz "-dc -T0") input))
>>      ('gzip         (filtered-port `(,%gzip "-dc") input))
>>      (else          (error "unsupported compression scheme" compression))))
>
> Parallel decompression isn't implemented yet, but the extra '-T0' option
> doesn't seem to break anything.
>
> The changes LGTM.
>
> I sent a companion patch to <https://bugs.gnu.org/26316> that enables
> threaded compression when building source tarballs.

Is (parallel-job-count) accessible here? It would be nice to respect it.