On Fri, Mar 31, 2017 at 01:56:37PM -0400, Kei Kebreau wrote:
> Leo Famulari <leo@famulari.name> 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.
> 
> LGTM as well.

AFAICT, this doesn't cause mass rebuilds.