I’m aware.

It also lacks compatibility with a lot of important C gems (not only or even predominantly because of the lack of a GIL, of course), which I’m pointing out has always impacted its adoption.

Then you should also be aware that it runs most of them via Sulong.

That’s Truffle, not JRuby. There was a plan several years ago to move Sulong support into JRuby based on trialing it in Truffle; it appears to have made no progress since 2016.

JRuby has no support for C extensions.

TruffleRuby supports C extensions, and has no GIL for Ruby code.

My personal experience with Ruby is extremely shallow, but a casual glance at the search results wrt the GIL in Ruby seems to say it actually does have one. I could be wrong, as I'm not an experienced Ruby developer, however.

I.e. https://thoughtbot.com/blog/untangling-ruby-threads

From your link: "Note that this is not the case for JRuby or Rubinius which do not have a GIL and offer true multi-threading."

Ruby has multiple implementations, JRuby uses Java Threads without any sort of GIL.

Plenty of talks done on this subject by Charles Nutter.