[Arnor]

> JRuby and Rubinius use native threads so you can use all cores with just Thread.new.

Almost. JRuby uses JVM threads so the actual threading model depends on the underline JVM.

[rubiquity]

What versions of the JVM don't map JVM threads directly to Os threads? I thought green threading was removed a long time ago. I would love more info, thank you.