Programming Ruby 3.3

Creating Fibers

Although the name “fibers” suggests some kind of lightweight thread, Ruby’s fibers are a mechanism for denoting a block of code that can be stopped and restarted, which is sometimes called a coroutine. Fibers in Ruby are cooperatively multitasked, meaning that the responsibility for yielding control rests with the individual fibers and not the operating system. Fibers can explicitly yield control, or be set to automatically yield control when its operations are blocked.

Fibers let you write programs that share control without incurring all of the complexity inherent in low-level threading. Let’s look at a simple example. We’d like to analyze a text file, counting the occurrence of each word. We could do this (without using fibers) ...