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Elixir & PhoenixFunctional |> Concurrent |> Pragmatic |> Fun
Who am I?
• Jared Smith
• Software Engineer at One Month
• @sublimecoder
• www.sublimecoding.com
Lets get started
First lets talk about Erlang
• Elixir runs on the Erlang VM
• Many of the standard lib function calls in Elixir call Erlang functions directly.
• Elixir piggy backs on the Erlang ecosystem
Why Erlang VM?
• 30 year old battle tested VM
• Highly available, fault tolerant, and distributed
History of Erlang
• Developed by Ericsson
• Used and developed for Telecommunications
• In fact its standard library is the OTP (Open Telecom Platform)
Telecommunications
• High availability is king
• Remote Telecom switches need to run for years sometimes with out being disturbed
Built with Erlang
• 50 person engineering team
• managing 900 million users.
• Up to 2 million active users per server.
https://blog.whatsapp.com/196/1-million-is-so-2011
2 Million Active Users?
• Intel Xeon CPU x5675 @ 3.07GHz 24 Cores - 96GB Ram
• Using only 40% of the CPU/Memory
https://blog.whatsapp.com/196/1-million-is-so-2011
So Erlang is pretty awesome
• Wouldn’t it be nice if we could harness this power?
• Why isn’t everyone using Erlang?
Elixir
• Elixir utilizes much of the power of Erlang
• While giving us a much nicer syntax and api to work with.
History of Elixir
• Created by Josè Valím - (Joe-zay Val-eem)
• First released in 2012
Elixir’s Strengths
• Concurrency
• Meta-programming Capability
• Transformation of data as a core ideal
Plus it has Ruby like syntax
Pipe Operator• The following code is valid elixir.
• With the pipe operator we can write our code this way instead. Keeping us out of nested function hell.
Pattern Matching
• Pattern matching is a core part of Erlang and Elixir
What is Pattern Matching?
• Make left side look like the right side
• a = 99
• [a,b,c] = [1,2,3]
• [head | tail] = [1,2,3]
Immutability
• Once you set a value it can never change.
Immutability
You’re already familiar with immutability you just don’t know it.
• a = 99
• We all know 99 is always 99.
• integers are immutable values, even in Ruby.
• You’d be upset if someone monkey patched 99 to be 3 right?
Why is Immutability a good thing?
• Immutability provides a contract that each piece of information has one source of truth.
• Concurrency is a natural side effect of immutability.
Does this mean I can never change a variable once I set it?
• The short answer is no, you can reassign variables as much as you like.
• Erlang would not be so kind, but Elixir we have this luxury.
So how is it immutable if I can change things?
• You can change things, elixir will just copy the values you don’t change, but the original reference stays intact.
• The original reference can then be used in part or in whole later in the application.
Isn’t this inefficient?
• At first glance it would seem that way, but the opposite is true.
• Won’t all the old reference values balloon elixirs memory?
• Yes this means you could have thousands of unused variables floating in memory
Concurrency
Concurrency fixes everything
• Because the data is immutable we can rely on it always being a certain value
• which means we can make our programs concurrent and not worry.
• Elixir uses its concurrency to help with garbage collections. Each process gets it own heap allocated and that heap is garbage collected or reclaimed as needed for that individual process.
Concurrency
• Elixir will eat as many cores/computers as you can throw at it.
• It treats each core as though it were a computer on the network with near zero latency.
Phoenix Framework Productive |> Reliable |> Fast
Phoenix Framework
• Created by Chris McCord
• Release 1.0 August 28th 2015
Phoenix Framework
• It’s not rails for Elixir
• It has been influence heavily by rails as well as many other frameworks.
• Focus on API and web sockets
Speed• Web request response time is often measured in
micro seconds and not milliseconds.
Benchmarks
• Recently benchmarked 2 million+ web socket connections
• With 2 - 3 second broadcast times to all 2 million connections
Benchmarks
https://github.com/mroth/phoenix-showdown
iMac Intel Core i7 (4.0 GHz 4 Cores) 32 GB RAM
https://github.com/mroth/phoenix-showdown
2.8 Ghz, 10 core Intel® Xeon 128 GB RAM
Easy Startup
• mix phoenix.new ./app/path/my_app
• mix ecto.create && mix ecto.migrate
• mix phoenix.server
Directory Structure
Web Dir Structure
Mix
• Mix is essentially bundler and rake combined
• Additionally mix is your test runner.
• It’s included with Elixir
Rails like Generators
• mix phoenix.gen.html Post posts title body:text
• mix phoenix.gen.json User users name:string
• mix phoenix.gen.model User users name:string
Concurrency
• Async processing with out the need for DelayedJob or Resque/sidekiq
• We can write code that looks like this.
Isolated & Concurrent
• Crashes are isolated
• Data is isolated (GC is per process, no global pauses)
• Load Balances on IO and CPU - Efficient on a multicore
Garbage Collection
• No triggering massive garbage collection
• GC per process / end of process life cycle
• Ensuring top 10 percent of requests are not vastly slower than any other request
Request Pipeline
• Just a series of function calls that transform data.
• connection |> endpoint|> router|> pipelines|> controller
Request Pipeline• Phoenix makes it easy to add middleware or
plugs to this pipeline. We could easily add authentication to this.
• connection |> endpoint|> router|> pipelines|> authenticate_user|> controller
Explicitness Over Magic
• Phoenix Removes a lot of the confusion and “magic” found in rails and replaces it with explicit calls.
• Models, Controllers and Views are singular named by convention.
Phoenix Router
Phoenix Router
Phoenix Router
Phoenix Controllers
Phoenix Model
Phoenix View
Phoenix Template
Learn More• Elixir-Lang on Slack
https://elixir-slackin.herokuapp.com/
• #elixir-lang on Freenode IRC
• http://www.phoenixframework.org
• http://elixir-lang.org/
• https://github.com/h4cc/awesome-elixir