Re: sphinx-build is really slow, any way to improve that?

[Peter Maydell]

On Tue, 6 Sept 2022 at 08:55, Daniel P. Berrangé <berrange@redhat.com> wrote:
>
> On Mon, Sep 05, 2022 at 10:21:55PM +0100, Peter Maydell wrote:
> > On Mon, 5 Sept 2022 at 20:51, Claudio Fontana <cfontana@suse.de> wrote:
> > > when I build qemu, there is a lot of time spent at the end of the build 
> > > where one cpu goes 100% on sphinx-build.
> > >
> > > Is there some way to parallelize that? It seems it is the current 
> > > bottleneck for rebuilds for me..
> >
> > It's a big fat python program, so I suspect not, but
> > maybe I'm wrong.
>
> It annoys me too and I've had a look at what it is doing in the past and
> failed to find an obvious way to improve it. I fear this could be an
> inherant limitation of the way we use sphinx to build the docs as a
> complete manual, as compared to say treating each docs source file as
> a distinct standalone web page.

IIRC sphinx really really wants to process the whole document tree
in one go. You can see this in the way that for example the
HTML build process creates HTML files for the top-level rst
files that are supposed to be only for the manpage -- it will
suck in and process everything, not just the files reachable
via whatever top level file you point it at.

-- PMM