On Thu, Dec 14, 2017 at 10:37:24PM +0100, Tobias Geerinckx-Rice wrote:
> * gnu/packages/compression.scm (plzip): New public variable.

> +    (synopsis "Parallel lossless data compressor for the lzip format")
> +    (description
> +     "Plzip is a massively parallel (multi-threaded) lossless data compressor
> +and decompressor that uses the lzip file format (.lz).  Files produced by plzip
> +are fully compatible with lzip and can be rescued with lziprecover.
> +On multiprocessor machines, plzip can compress and decompress large files much
> +faster than lzip, at the cost of a slightly reduced compression ratio (0.4% to
> +2%).  The number of usable threads is limited by file size: on files of only a
> +few MiB, plzip is no faster than lzip.
> +Files that were compressed with regular lzip will also not be decompressed
> +faster by plzip, unless the @code{-b} option was used: lzip usually produces
> +single-member files which can't be decompressed in parallel.")

Maybe this would be useful in ((guix packages) patch-and-repack), (guix
utils) and (guix scripts pack). In those modules, we compress XZ
archives in parallel to speed it up.