That depends on the Ruby implementation. MRI (CRuby) has a GVL which is why you might use a forking web server like Puma or Pitchfork. JRuby and TruffleRuby t

That depends on the Ruby implementation. MRI (CRuby) has a GVL which is why you might use a forking web server like Puma or Pitchfork. JRuby and TruffleRuby though have true multi-threading and no GVL. I’ve used the Concurrent Ruby library with JRuby and Tomcat quite a bit and find works very well for what I need.