[arch-general] Multithreaded XZ

[Jan Alexander Steffens]

On Mon, Dec 22, 2014 at 3:25 AM, Mark Lee <mark at markelee.com> wrote:
> Now that xz is multithreaded (not available in Arch Repos yet); I was
> wondering if package building and installing would, by default,
> utilize multiple threads.

It won't, since the output of XZ in multi-threaded mode is different
from single-threaded mode. This will break anything relying on getting
repeatable output from compression. I'm not even sure it's possible to
run XZ in multi-threaded mode with a single thread. xz -T1 uses
single-threaded mode. xz -T1 --block-size=24M is also different from
xz -T2 --block-size=24M.

Multi-threaded decompression also requires a stream created using
multi-threaded mode.