Multiprocessor support for `xz`?

Multiprocessor (multithreading) compression support was added to xz in version 5.2, in December 2014.

To enable the functionality, add the -T option, along with either the number of worker threads to spawn, or -T0 to spawn as many CPU’s as the OS reports:

xz -T0 big.tar
xz -T4 bigish.tar

The default single threaded operation is equivalent to -T1.

I have found that running it with a couple of hyper-threads less than the total number of hyperthreads on my CPU^† provides a good balance of responsiveness and compression speed.

^{† So -T10 on my 6 core, 12 thread workstation.}

As scai and Dzenly said in comments

If you want to use this in combination with tar just call export XZ_DEFAULTS="-T 0" before.

or use smth like: XZ_OPT="-2 -T0"