Rubyconfph 2014 talk on parallel programming. Demo can be found at: https://github.com/sudizhe/parallel_programming_demo

1. Parallel
Computing
with ruby

2. My Company

3. My Company

4. Challenges

5. • Learning Ruby
Challenges

6. • Learning Ruby
• Rails 2 to Rails 3
Challenges

7. • Learning Ruby
• Rails 2 to Rails 3
• Integrating with Banking APIs
Challenges

8. What is Parallel
Computing?

9. Multithreading!
vs!
Multiprocessing

10. Share Memory Space!
Lightweight!
May Have Memory
Management Issues!
Can Sometimes Take
Advantage of Multiple
CPUs
Thread Process
Separate Memory Space!
Requires More Memory!
No Multithreading
Issues!
Can Take Advantage of
Multiple CPUs

11. CPU Scheduling
High IO
High CPU
http://www.cs.rutgers.edu/~pxk/416/notes/07-scheduling.html

12. High I/O
High IO
Fill these I/O blocks with other CPU tasks!

13. Multithreading ticker
t1 = Thread.new do
puts "[Thread 1] Started"
sleep 2
puts "[Thread 1] Completed"
end
!
t2 = Thread.new do
5.times do |n|
puts "[Thread 2] tick #{n}"
end
end

14. Multithreading ticker
t1 = Thread.new do
puts "[Thread 1] Started"
sleep 2
puts "[Thread 1] Completed"
end
!
t2 = Thread.new do
5.times do |n|
puts "[Thread 2] tick #{n}"
end
end
$ ruby thread_ticker.rb
[Thread 1] Started
[Thread 2] tick 0
[Thread 2] tick 1
[Thread 2] tick 2
[Thread 2] tick 3
[Thread 2] tick 4

15. Multithreading ticker
t1 = Thread.new do
puts "[Thread 1] Started"
sleep 2
puts "[Thread 1] Completed"
end
!
t2 = Thread.new do
5.times do |n|
puts "[Thread 2] tick #{n}"
end
end
Where’s Completed ?
$ ruby thread_ticker.rb
[Thread 1] Started
[Thread 2] tick 0
[Thread 2] tick 1
[Thread 2] tick 2
[Thread 2] tick 3
[Thread 2] tick 4

16. Multithreading ticker
t1 = Thread.new do
puts "[Thread 1] Started"
sleep 2
puts "[Thread 1] Completed"
end
!
t2 = Thread.new do
5.times do |n|
puts "[Thread 2] tick #{n}"
end
end
!
t1.join
t2.join

17. Multithreading ticker
t1 = Thread.new do
puts "[Thread 1] Started"
sleep 2
puts "[Thread 1] Completed"
end
!
t2 = Thread.new do
5.times do |n|
puts "[Thread 2] tick #{n}"
end
end
!
t1.join
t2.join
$ ruby thread_ticker.rb
[Thread 1] Started
[Thread 2] tick 0
[Thread 2] tick 1
[Thread 2] tick 2
[Thread 2] tick 3
[Thread 2] tick 4
[Thread 1] Completed

18. Issues with Threads
No control when Threads are preempted!
Deadlock!
Race conditions!
Hard to debug

19. Race Condition

20. Race Condition

21. Race Condition

22. Fibers

23. Fibers
Programmers specify when to give up control!
Prevents concurrency issues!
Lightweight

24. Fibers vs Threads
http://oldmoe.blogspot.com/2008/08/ruby-fibers-vs-ruby-threads.html

25. Fibonacci
fib = Fiber.new do
f1 = f2 = 1
loop do
Fiber.yield f1
f1, f2 = f2, f1 + f2
end
end
!
5.times { p fib.resume }
$ ruby fiber_fib.rb
1
1
2
3
5

26. Fiber Ticker
require 'fiber'
!
fb1 = Fiber.new do
puts "[Fiber 1] Started"
sleep 2
puts "[Fiber 1] Completed"
end
!
fb2 = Fiber.new do
5.times do |n|
puts "[Fiber 2] tick #{n}"
end
end
!
fb1.resume
fb2.resume

27. Fiber Ticker
require 'fiber'
!
fb1 = Fiber.new do
puts "[Fiber 1] Started"
sleep 2
puts "[Fiber 1] Completed"
end
!
fb2 = Fiber.new do
5.times do |n|
puts "[Fiber 2] tick #{n}"
end
end
!
fb1.resume
fb2.resume
$ ruby fiber_tick.rb
[Fiber 1] Started
[Fiber 1] Completed
[Fiber 2] tick 0
[Fiber 2] tick 1
[Fiber 2] tick 2
[Fiber 2] tick 3
[Fiber 2] tick 4
http://schmurfy.github.io/2011/09/25/on_fibers_and_threads.html

28. Event Machine
https://github.com/eventmachine/eventmachine

29. Evented Ticker
require 'fiber'
require 'eventmachine'
!
EM::run do
fb1 = Fiber.new do
puts "[Fiber 1] Started"
EM::add_timer(2){ fb1.resume }
Fiber.yield
puts "[Fiber 1] Completed"
EM::stop()
end
!
fb2 = Fiber.new do
5.times {|n| puts "[Fiber 2] tick #{n}" }
end
!
fb1.resume
fb2.resume
end
$ ruby evented_ticker.rb
[Fiber 1] Started
[Fiber 2] tick 0
[Fiber 2] tick 1
[Fiber 2] tick 2
[Fiber 2] tick 3
[Fiber 2] tick 4
[Fiber 1] Completed

30. When does
Multithreading help?
High I/O time such as
File I/O DB call API request

31. Demo
https://github.com/sudizhe/parallel_programming_demo

32. Fibers
Programmers specify when to give up control!
Prevents concurrency issues!
Lightweight

33. Multiprocessing?
http://www.igvita.com/2008/11/13/concurrency-is-a-myth-in-ruby/

34. Multiprocessing?
http://www.igvita.com/2008/11/13/concurrency-is-a-myth-in-ruby/
Global Interpreter Lock (GIL)

35. Multiprocessing?
http://www.igvita.com/2008/11/13/concurrency-is-a-myth-in-ruby/
Global Interpreter Lock (GIL)

36. Rails Deploy

37. Spawning Processes

38. Parallel Gem

39. inDinero Enterprise

40. inDinero Enterprise
150,000 Transactions

41. inDinero Enterprise
150,000 Transactions x 15,000 Rules

43. Recap
Multithreading
Thread Class
Fibers
Event Machine
Multiprocessing
Process Class
Unicorn Magic
Hadoop

44. Q & A