Concurrency patterns in Ruby

Ruby is a wonderful language for rapid development, it is easy to learn, we have wonderful frameworks, an active and dynamic community. But when it comes to concurrency Ruby is plagued with problems, controversies and urban legends. A lot of people would know about green threads in Ruby, GIL and its inherent limitations. But that it only one part of the big picture. Ruby offers much more than threads to helps us with concurrency.

This presentation explores other options of writing highly concurrent applications in Ruby and options available in it. We cover topics ranging from Actor like message passing concurrency in Ruby, dataflow concurrency of how we can coordinate across different threads, Event driven methods, coroutine based concurrency which never blocks ;) and finally Software Transactional Memory. We look at lots of code, some serious looking yet colorful performance graphs comparisons, and conditions at which each of these forms are concurrency are effective and ineffective.

Talk by @sai_venkat & @harikrishnan83

Transcript

1. Paradigms of Concurrency
2. Why is this important?
3. Or for geeks to relate...
5. Without right abstractions...
6. So what do we have in hand? • Threads – The Java hangover • Fibers – Red headed cousin of threads • Actors – Stylish but effective • Reactor – He will do all the work... • Dataflow – The forgotten one.. • STM – Remember ATM • The Nirvana
7. A folk definition of insanity is to do the same thing over and over again and to expect the results to be different. By this definition, we in fact require that programmers of multithreaded systems be insane - The Problem with Threads Edward Lee
8. Threading in Ruby Concurrency is a myth Ruby - @igvita
10. Fibers • New kid in the block from Ruby 1.9 • Green threads with cooperatively scheduler • Can give up CPU control to other fiber when needed. • Based on Coroutines – Like python generators but can yield to other coroutines • Think NeverBlock...
11. Nginx vs Apache Death Match
12. EventMachine – Reactor Pattern
13. EventMachine • Based on python Twisted • Reactor sits in the middle • IOC pattern – Not many get used to it • Defer long running process • Support for lot of protocols and very active development • Try my em-couchdb :) (http://github.com/saivenkat/em- couchdb)
14. Actors -Stylishly passing messages
15. Actors • Message passing concurrency • No first class support in Ruby • Revactor is good but we had problems with it • If Jruby, lots of Java Actor framework available like Jetlang. • Jruby + Jetlang - http://bit.ly/ahXh6j
16. Transactions – We are safe
17. Software Transactional Memory • Similar to database transactions but inmemory (ACID XX ) • Unfortunately again no first class support • STM library by MentalGuy - http://bit.ly/c7Mxah • In Jruby harness clojure's infrastructure – Ruby objects as refs. http://bit.ly/d6vpuP
18. Multi Process
19. Coordination
20. Coordination • How do we coordinate independent units of execution? • Dataflow – Forgotten paradigm • Other methods – May be a big heavy weight suitable when multi processing • Tuplespace, Queues (RabbitMq or beanstalk)
21. Nirvana
22. Nirvana • Polyglotism – Let the languages which excel in concurrency do the job • Make Ruby talk with Clojure, Erlang, Haskell, node.js... • Lots of ways. VM level support, external infrastructure.
23. Sai Venkat github.com/saivenkat @sai_venkat http://developer-in-test.blogspot.com HariKrishnan github.com/harikrishnan83 @harikrishnan83 http://harikrishnan83.wordpress.com
24. All images used are attributed to the awesome guys who took them.. Please don't sue us :D