This document discusses Rhebok, a high performance Rack handler written in Ruby. Rhebok uses a prefork architecture for concurrency and achieves 1.5-2x better performance than Unicorn. It implements efficient network I/O using techniques like IO timeouts, TCP_NODELAY, and writev(). Rhebok also uses the ultra-fast PicoHTTPParser for HTTP request parsing. The document provides an overview of Rhebok,