Reasonable Concurrency with Actors and Elixir

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Reason-able Concurrency with Actors

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Reasonable “able to think, understand, or form judgments by a logical process.”

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Concurrency

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What are we here for? (besides beer)

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What are we here for? Context

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What are we here for? Context Opinionated Statement

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What are we here for? Context Opinionated Statement Moralize

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What are we here for? Context Opinionated Statement Moralize repeat

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Context

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Holding things in your head is hard

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Elixir

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Elixir “Dynamic, Functional language designed for building scalable and maintainable applications”

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Elixir Erlang VM

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Erlang VM Immutable Data Structures Elixir

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Erlang VM Immutable Data Structures Pattern Matching Elixir

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Erlang VM Immutable Data Structures Pattern Matching Hygienic Macros Elixir

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Erlang VM Immutable Data Structures Pattern Matching Hygienic Macros “Green” Processes Elixir

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#1 Elixir is OO

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#1 Elixir is OO And thats a good thing

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Object Oriented: the good parts

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smallTalk-72

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Message Passing

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Boundaries

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Encapsulate Errors

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Processes FTW.

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“concurrent processes with no data sharing provide a strong measure of fault isolation. A software error in a concurrent process should not influence processing in the other processes in the system.” - Joe Armstrong

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“As soon as two processes share any common resource…the possibility exists that a software error in one of the processes will corrupt the shared resource. Since eliminating all such software errors for large software systems is an unsolved problem I think that the only realistic way to build large reliable systems is by partitioning the system into independent parallel processes, and by providing mechanisms for monitoring and restarting these processes” - Joe Armstrong

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OTP

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OTP Actors

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OTP Actors Messages + Mailboxes

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OTP Actors Messages + Mailboxes Hot code swapping

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Moralizing

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State is in your app

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State Should be small

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State should be hidden

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#2 Failure

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#2 Failure Its time to get over it

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Failures are latent

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Failures are latent “The complexity of these systems makes it impossible for them to run without multiple flaws being present"

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Failures are latent “The high consequences of failure lead over time to the construction of multiple layers of defense against failure…The effect of these measures is to provide a series of shields that normally divert operations away from accidents”

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Supervisors

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Supervisor Stack

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Persistance

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Supervisor Stack Database

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Moralizing

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Failures Will Happen

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Failures should be

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Failures should be Seen

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Failures should be Seen Isolated

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Supervise Complexity

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Supervision Hierarchy

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Intentional Programming

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Let it Fail

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Thanks