Introduction to Erlang - Speaker Deck

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Introduction to Erlang Michał Ślaski @michalslaski ! ! ! AKAI Camp Backend, Poznań, 28.10.2014

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Erlang timeline and my background

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Erlang timeline and my background Started out in the Ericsson software lab 1987 (!)

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Erlang timeline and my background Started out in the Ericsson software lab 1987 (!) • I was six years old 

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Erlang timeline and my background Started out in the Ericsson software lab 1987 (!) • I was six years old  Released as open source in 1998

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Erlang timeline and my background Started out in the Ericsson software lab 1987 (!) • I was six years old  Released as open source in 1998 • I started computer science at AGH 2 years later 

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Erlang timeline and my background Started out in the Ericsson software lab 1987 (!) • I was six years old  Released as open source in 1998 • I started computer science at AGH 2 years later  Gains SMP support in 2005

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Erlang properties

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Erlang properties Declarative • Functional programming language • high abstraction level • pattern matching • concise and readable programs

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Erlang properties -‐ functions Modules & Functions -module(demo). -export([double/1]). % This is a comment. % Everything after '%' is ignored. double(X) -> times(X, 2). times(X, N) -> X * N.

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Erlang properties

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Erlang properties Concurrency • light-‐weight processes (actor model) • highly scalable   

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Erlang properties Concurrency • light-‐weight processes (actor model) • highly scalable    Soft real-‐time • response times in the order of milliseconds • per process garbage collection

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Erlang properties -‐ processes

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Erlang properties -‐ processes

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Erlang properties -‐ processes Pid = spawn(M, F, A)

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Erlang properties -‐ processes Pid = spawn(M, F, A)

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Erlang properties -‐ processes Pid = spawn(M, F, A) receive! {msg, From} ->! From ! ok! end

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Erlang properties -‐ processes Pid = spawn(M, F, A) receive! {msg, From} ->! From ! ok! end Pid ! {msg, self()}

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Erlang properties -‐ processes Pid = spawn(M, F, A) receive! {msg, From} ->! From ! ok! end Pid ! {msg, self()} ok

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Erlang properties Robustness • simple and consistent error recovery • supervision hierarchies • program for the correct case • let it crash

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Erlang properties -‐ supervision tree

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Erlang properties -‐ supervision tree

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Erlang properties -‐ supervision tree

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Erlang properties -‐ supervision tree supervisor

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Erlang properties -‐ supervision tree supervisor worker

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Erlang properties -‐ supervision tree supervisor worker

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Erlang properties -‐ supervision tree supervisor worker

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Erlang properties -‐ supervision tree supervisor worker

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Erlang properties Distribution • explicit or transparent distribution • network-‐aware runtime system

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Erlang properties -‐ distribution

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Erlang properties -‐ distribution cat

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Erlang properties -‐ distribution cat ﬂea

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Erlang properties -‐ distribution cat ﬂea nodes() = [cat@home, flea@home]

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Erlang properties -‐ distribution cat dog ﬂea bird nodes() = [cat@home, flea@home]

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Erlang properties -‐ distribution cat dog ﬂea bird nodes() = [cat@home, flea@home] nodes() = [dog@home, bird@home]

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Erlang properties -‐ distribution cat dog ﬂea bird nodes() = [cat@home, flea@home] nodes() = [dog@home, bird@home]

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Erlang properties -‐ distribution cat dog ﬂea bird nodes() = [cat@home, flea@home, dog@work, bird@work]

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Erlang properties

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Erlang properties Hot code loading • easily change code in a running system • enables non-‐stop operation • simplifies testing 

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Erlang properties Hot code loading • easily change code in a running system • enables non-‐stop operation • simplifies testing  SMP support • takes advantage of multiple CPU architectures 

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Erlang properties Hot code loading • easily change code in a running system • enables non-‐stop operation • simplifies testing  SMP support • takes advantage of multiple CPU architectures  Erlang Shell • access from remote nodes

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Erlang properties

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Erlang properties External interfaces • "Ports" to the outside world  behave as Erlang processes 

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Erlang properties External interfaces • "Ports" to the outside world  behave as Erlang processes  Portability • Erlang runs on Unix, Linux, Mac OS X, Windows • RaspberryPi and Parallella

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Demo time!

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Demo -‐ SMP $ erl -smp disable Erlang/OTP 17 [erts-6.1] [source-d2a4c20] [async-threads:10]  [hipe] [kernel-poll:false] ! Eshell V6.1 (abort with ^G)   1> F = fun(Int) -> pmap:factorial(Int) end. #Fun  2> timer:tc(lists, map, [F,lists:seq(1, 5000)]). {12570092, [1,2,6,24,120,720,5040,40320,362880,3628800|...]}   3> timer:tc(pmap, pmap, [F,lists:seq(1, 5000)]). {21511918, [1,2,6,24,120,720,5040,40320,362880,3628800|...]}   4> element(2, v(2)) == element(2, v(3)). true

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Demo -‐ SMP $ erl -smp enable Erlang/OTP 17 [erts-6.1] [source-d2a4c20] [smp:4:4]  [async-threads:10] [hipe] [kernel-poll:false] ! Eshell V6.1 (abort with ^G) ! 1> F = fun(Int) -> pmap:factorial(Int) end. #Fun ! 2> timer:tc(lists, map, [F,lists:seq(1, 5000)]). {12535610, [1,2,6,24,120,720,5040,40320,362880,3628800|...]} ! 3> timer:tc(pmap, pmap, [F,lists:seq(1, 5000)]). {9159734, [1,2,6,24,120,720,5040,40320,362880,3628800|...]}

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Demo -‐ SMP no SMP SMP map 12.5s 12.5s parallel map 21.5s 9.2s

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Demo -‐ SMP no SMP SMP map 12.5s 12.5s parallel map 21.5s 9.2s

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Demo -‐ SMP no SMP SMP map 12.5s 12.5s parallel map 21.5s 9.2s 230%

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Open source projects

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Open source projects • RabbitMQ message broker  

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Open source projects • RabbitMQ message broker   • MongooseIM XMPP server 

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Open source projects • RabbitMQ message broker   • MongooseIM XMPP server  • Riak database 

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Open source projects • RabbitMQ message broker   • MongooseIM XMPP server  • Riak database  • CouchDB database

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Erlang community

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Erlang community Erlang Central • www.erlangcentral.org 

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Erlang community Erlang Central • www.erlangcentral.org  Erlang Factory • Berlin, December 4 • San Francisco, March 26-‐27 

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Erlang community Erlang Central • www.erlangcentral.org  Erlang Factory • Berlin, December 4 • San Francisco, March 26-‐27  Lambda Days • Kraków, February 26-‐27

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Questions? ! Michał Ślaski @michalslaski