Celluloid & DCell - Speaker Deck

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Celluloid DCell &

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@vanstee github.com/vanstee Patrick Van Stee highgroove.com

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@tarcieri Revactor Reia nio4r Cryptosphere cool.io

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brew install zeromq gem install dcell Setup

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Celluloid General purpose concurrency framework for Ruby built on the Actor Model

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class Counter attr_reader :count def initialize @count = 0 end def increment @count += 1 end end

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class Counter attr_reader :count def initialize @count = 0 @mutex = Mutex.new end def increment @mutex.synchronize do @count += 1 end end end

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Threads are hard!

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class Counter include Celluloid attr_reader :count def initialize @count = 0 end def increment @count += 1 end end

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Actor Model

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•No shared state •Communicate with messages •Process messages sequentially

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class Counter include Celluloid def increment(count, actor) return count if count < 10000 actor.increment( count + 1, Actor.current ) end end

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& Asynchronous Method Calls Futures

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counter = Counter.new # returns immediately counter.increment! puts counter.count # returns immediately future = counter.future :increment puts future.value

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module Enumerable def map(&block) futures = map do |item| Celluloid::Future.new( item, &block ) end futures.map(&:value) end end

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Caveats

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• The GIL in MRI does not allow parallelism • Threads and Fibers are expensive • Concurrency is still a hard problem [not really]

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DCell

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Celluloid General purpose concurrency framework for Ruby built on the Actor Model DCell Distributed Celluloid over 0MQ

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“I thought of objects being like biological cells or individual computers on a network, only able to communicate with messages. Alan Kay