Concurrent computing in Julia based on the Actor Model
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Started In
January 2016


Concurrent computing in Julia with actors.

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Actors implements the Actor Model of computation:

An actor ... in response to a message it receives, can concurrently:

  • send a finite number of messages to other actors;
  • create a finite number of new actors;
  • designate the behavior to be used for the next message it receives.

Actors make(s) concurrency easy to understand and reason about and integrate(s) well with Julia's multi-threading and distributed computing. It provides an API for writing reactive applications, that are:

  • responsive: react to inputs and events,
  • message-driven: rely on asynchronous message-passing,
  • resilient: can cope with failures,
  • elastic: can distribute load over multiple threads and workers.

Greeting Actors

The following example defines two behavior functions: greet and hello and spawns two actors with them. sayhello will forward a message to greeter, get a greeting string back and deliver it as a result:

julia> using Actors

julia> import Actors: spawn

julia> greet(greeting, msg) = greeting*", "*msg*"!" # a greetings server
greet (generic function with 1 method)

julia> hello(greeter, to) = request(greeter, to)    # a greetings client
hello (generic function with 1 method)

julia> greeter = spawn(greet, "Hello")              # start the server with a greet string
Link{Channel{Any}}(Channel{Any}(sz_max:32,sz_curr:0), 1, :default)

julia> sayhello = spawn(hello, greeter)             # start the client with a link to the server
Link{Channel{Any}}(Channel{Any}(sz_max:32,sz_curr:0), 1, :default)

julia> request(sayhello, "World")                   # request the client
"Hello, World!"

julia> request(sayhello, "Kermit")
"Hello, Kermit!"

Please look into the manual for more information and more serious examples.


Actors is part of the Julia GitHub group JuliaActors. Please join!


  • Oliver Schulz (until v0.1, Oct 2017)
  • Paul Bayer (rewrite since v0.1.1, Nov 2020)



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