[bjfish]

Hello, post author here. What I mean by "N/A" here is "Not Applicable" as in Ruby was not designed for concurrency. I didn't mean to say that it is "Not Available" or not possible. I also was only describing language features without considering libraries.

Even JRuby's first recommendation for concurrency is "don't do it": https://github.com/jruby/jruby/wiki/Concurrency-in-jruby

[sciurus]

So, you're saying threads and coroutines aren't concurrency?

[weatherlight]

I'm pretty sure Matz is still working at re-architecting the Ruby global interpreter lock (GIL) for genuine concurrency. JRuby and Rubinius are alternative Implementations of ruby that do support Concurrency, but they are just that, alternative Implementations.