Overview of Actor based programming. Given at the Penn State WebConference 2016.

1. Actor Systems
Derek Morr
@derekmorr

2. A style of programming, not a language
Erlang / Elixir (BEAM)
Akka (JVM, .NET)
Orleans (.NET)
Celluloid (Ruby)
Pulsar (Python)
Cloud Haskell (Haskell)
Pony

3. Herb Sutter,
“The Free Lunch is Over”
March 2005

4. John Appleby,
April 2013
Clock speed is flat
Core count is going up

7. Adapteva Parallela
18 cores
$100

8. Where:
S(n) = speedup
P = parallel portion of the program
n = number of threads

9. Serial portion Parallel portion
Run time

10. Serial portion Parallel portion
Serial portion
Parallel portion
Parallel portion

11. Serial portion Parallel portion
Serial portion
Serial portion
Parallel portion
Parallel portion

12. Serial portion Parallel portion
Serial portion
Serial portion
Serial portion
Parallel portion
Parallel portion

13. Serial portion Parallel portion
Serial portion
Serial portion
Serial portion
Serial portion
Parallel portion
Parallel portion

14. Serial portion Parallel portion
Serial portion
Serial portion
Serial portion
Serial portion
Serial portion
Parallel portion
Parallel portion

16. def a() = {
// do stuff
b()
}
def b() = {
// do stuff
c()
}
def c() = {
// do stuff
throw new Exception("kaboom")
}

17. def a() = {
// do stuff
b()
}
def b() = {
// do stuff
c()
}
def c() = {
// do stuff
throw new Exception("kaboom")
}

18. def a() = {
// do stuff
b()
}
def b() = {
// do stuff
c()
}
def c() = {
// do stuff
throw new Exception("kaboom")
}

19. def a() = {
// do stuff
b()
}
def b() = {
// do stuff
c()
}
def c() = {
// do stuff
throw new Exception("kaboom")
}

20. def a() = {
// do stuff
b()
}
def b() = {
// do stuff
c()
}
def c() = {
// do stuff
throw new Exception("kaboom")
}

21. def a() = {
// do stuff
b()
}
def b() = {
// do stuff
c()
}
def c() = {
// do stuff
throw new Exception("kaboom")
}

22. def a() = {
// do stuff
b()
}
def b() = {
// do stuff
c()
}
def c() = {
// do stuff
throw new Exception("kaboom")
}

23. def a() = {
// do stuff
b()
}
def b() = {
// do stuff
c()
}
def c() = {
// do stuff
throw new Exception("kaboom")
}

24. def a() = {
// do stuff
b()
}
def b() = {
// do stuff
c()
}
def c() = {
// do stuff
throw new Exception("kaboom")
}

25. def a() = {
// do stuff
b()
}
def b() = {
// do stuff
c()
}
def c() = {
// do stuff
throw new Exception("kaboom")
}

26. And then you crash!

27. {commingling
No isolation!

31. When an actor receives a message, it can:
● Make more actors
● Send messages to actors
● Change its internal state
● Take some side-effecting action (I/O)
Messages must be immutable.
Messaging is asynchronous.

35. Demo
Source at
https://github.com/derekmorr/helloactor

42. Error kernel pattern

43. Joe Armstrong’s Design Philosophy
The world is concurrent.
Things in the world don't share data.
Things communicate with messages.
Things fail.

44. Time for code
Source at
https://github.com/derekmorr/server_demo

45. Resources