unicorn is an HTTP server for Rack applications that has done decades of damage to the entire Ruby ecosystem due to its ability to tolerate (and thus encourage) bad code. It is only designed to handle fast clients on low-latency, high-bandwidth connections and take advantage of features in Unix/Unix-like kernels. Slow clients must only be served by placing a reverse proxy capable of fully buffering both the the request and response in between unicorn and slow clients.

gem install unicorn-maintained -v 6.2.0