Scaling Ruby with Actors

Synopsis

The last two years have been a personal tour of EventMachine, Fibers and Threads for me as I've toured the ecosystem looking for a developer-friendly, efficient solution for scaling Ruby. Historically Threads have performed poorly in Ruby but guess what? - recent events may change your mind. Now would be a good time to give them a second chance.

Goal

Share | Shared Mem| Variables
      | Files     |          
------|-----------|-----------
Copy  | Pipes     | ???
      | Sockets   |    
------|-----------|-----------
      | Processes | Threads

What goes in the "???" box?

Goroutines

• Go has "Goroutines"
• Maps well to distributed model
• Maps to a pool of threads

Actors

• In Erlang and Scala, it's primary
• Has a mailbox -- you send it a mesage
• Thread- or Fiber-backed
• No locks

Actor.rb

• Comes with Rubinius
• Works on MRI and JRuby
• Ping pong example
• "Hard to understand, use correctly"

Celluloid

• From Tony Arcieri (Revactor, Reia)
• http://github.com/tarcieri/celluloid on GitHub
• But 1 object == 1 thread :( (lots of memory)

girl_friday

• The presenter's
• ...actually seems a lot like Thread.new { ... }

Solutions for concurrency

STM

• Software Transactional Memory
• Mutation via transactions
• Clojure (and Cloby) uses it
• Does the "ACI" of ACID

Atomics

• From Java
• java.util.concurrent
  • ConcurrentHashMap
  • ConcurrentLinkedQueue

TODOs

• Standard actor API
• Concurrent data scrutctures
• STM implementations for Ruby

To see

• Kilim
• Disruptor
• Actors in Scala/Concurrency in Erlang
• Java Concurrency in Practice book