Open Stack

Hi all,

We recently merged a change [1] that will run the 
build-openstack-releasenotes job with 'sphinx-build -j auto' to allow 
the build to run on multiple CPUs. With the recent releases of reno 
3.1.0 and openstackdocstheme 2.1.2, both libraries advertise that they 
are parallel_read_safe and thus can support the '-j' option.

This effort was inspired by the nova build-openstack-releasenotes job
which typically takes 52m to > 1h to run. The job timeout is 1h, so we
were occasionally seeing TIMED_OUT job failures.

With parallel sphinx-build, the nova job run time is reduced down to 
about 15m (awesome!).

I wanted to say thanks to smcginnis, dhellmann, clarkb, and AJaeger for 
helping this newbie to reno and docs builds.

If anyone encounters any issues around the parallel reno builds in their 
projects, please let us know.

Cheers,
-melanie

[1] https://review.opendev.org/727473