On Sun, Mar 17, 2019 at 12:50 PM Dirk H√ľnniger <dirk.hunniger@googlemail.com> wrote:
A Chromium based solution is certainly one
of the best you can get. Its cheap in computational resources and
updates should be available for a long time.

I think computationally it's actually more expensive (OCG transformed the wikitext syntax tree into TeX, while Chromium does full HTML layouting). That's one of the reasons PDF rendering for collections is not avaible anymore; Chromium would just crash when trying to render a thousand-page book.

On the other hand, Chromium-rendered PDF will actually look the way it looks in the browser, without any maintenance effort needed (other than occasional tweaks to the print CSS), while with non-browser-based tools every template, extension and wikitext feature that had a visual component required dedicated handling, and common layout concepts like tables or multiple columns were extremely hard to get right.
 
I just figured out from the following link
that the new renderer was based on mwlib and reportlab.

Neither of those are mentioned on the page though.

I think the WMF ran its own mwlib service a long time ago (2013-ish?) but it didn't work well and was replaced by OCG (which eventually proved unmaintainable due to the above issues and lack of resourcing).