Itsi Scheduler

Itsi Scheduler is an implementation of a Ruby Fiber Scheduler.

When combined with Itsi Server, you can write endpoints that look just like regular synchronous Ruby code. Behind the scenes, the scheduler will transparently pause and resume fibers to prevent threads from blocking, greatly increasing throughput for I/O-heavy workloads

If you’re purely after a lightweight, yet efficient Ruby scheduler, you can use Itsi Scheduler as a standalone scheduler for any Ruby application.

Just use Fiber.set_scheduler to set an instance Itsi::Scheduler as a scheduler to opt in to this IO weaving behavior automatically for all blocking IO.

Primer on Fiber Schedulers

Fiber schedulers are a way to automatically manage the execution of non-blocking fibers in Ruby. A scheduler is responsible for the automatic pausing and resumption of Fibers based on whether or not they are awaiting IO operations. Ruby’s Fiber scheduler implementation automatically invokes the current Fiber scheduler (if it exists) for each blocking operation, allowing it to seamlessly drive the execution of huge numbers of simultaneous non-blocking fibers while ensuring the main thread is never blocked on IO.

This behind the scenes magic allows Ruby to provide async IO (just like we find in languages with async/await like Rust, C#, JavaScript) but with the added beauty that synchronous and asynchronous code is identical! (i.e. Ruby’s functions are colorless)

Getting Started

To install and use Itsi Scheduler follow the below instructions:

apt-get install build-essential libclang-dev

gem install itsi-scheduler

gem install itsi-scheduler

require 'itsi/scheduler'
require 'socket'
results = Thread.new do
  Fiber.set_scheduler Itsi::Scheduler.new
  results = []
  Fiber.schedule do
    results << Addrinfo.getaddrinfo("www.ruby-lang.org", 80, nil, :STREAM)
  end
  Fiber.schedule do
    results << Addrinfo.getaddrinfo("www.google.com", 80, nil, :STREAM)
  end
  results
end.value

puts results.map(&:inspect)