Talking about ruby community, thread safty was too late it's only usable in ruby 2.x and rails v. 4. And even with rails v4 many apps are not thread safe like

Talking about ruby community, thread safty was too late it's only usable in ruby 2.x and rails v. 4. And even with rails v4 many apps are not thread safe like canvas lms because the long tail of rails addons that are not thread safe and the common bad practice of using static properties to store non-sharable states and properties