The Digital Press

Ruby offers multiple concurrency models—processes, Ractors, threads, and fibers—each with different approaches to parallelism and memory management. While Ruby threads are limited by the Global Interpreter Lock (GIL), the newer Ractor model enables true parallel execution with isolated memory.

Why it matters: Understanding Ruby’s concurrency layers helps developers choose the best model for performance and safety in their applications.

The big picture: Processes and Ractors provide memory isolation and parallelism, threads offer concurrency with shared memory, and fibers enable lightweight cooperative multitasking.

The stakes: Misusing threads without synchronization risks race conditions; Ractors are experimental and not yet widely adopted in Ruby gems.

Commenters say: Users note Ruby threads are OS-managed, not green threads, and highlight the complexity of achieving true parallelism due to the GIL limitation.