How to get information

Actors are implemented as Julia Tasks running asynchronously and are represented by a messaging Link to them or by a registered name.

about an actor

You can use an actor's link (or its registered name) to get information about it:

julia> using Actors

julia> import Actors: spawn

julia> myBehavior(lk, f, args...) = send(lk, f(args...))
myBehavior (generic function with 1 method)

julia> me = newLink()
Link{Channel{Any}}(Channel{Any}(32), 1, :local)

julia> myactor = spawn(myBehavior, me)
Link{Channel{Any}}(Channel{Any}(32), 1, :default)

julia> info(myactor)
Actor    default
Behavior myBehavior
Pid      1, Thread 1
Task     @0x000000010d944230
Ident    x-d-ukih-hamub

info gives you some information about your actor. The system will on each worker pid identify an actor as a Julia Task. In order make it better identifiable for a human, the task address is also given as a Proquint identifier:

julia> using Proquint

julia> quint2uint("x-d-ukih-hamub")
0x000000010d944230

julia> info(myactor).task
0x000000010d944230

If you register an actor, you can use its registered name to get the information. Then info will show also the actor's name:

julia> register(:myname, myactor)
true

julia> info(:myname)
Actor    default
Behavior myBehavior
Pid      1, Thread 1
Task     @0x000000010d944230
Ident    x-d-ukih-hamub
Name     myname

about an actor's task

There are two ways to get the Task variable from an actor:

1. you spawn it with a taskref keyword argument or
2. you use Actors.diag.

julia> t = Ref(Actors.diag(myactor, :task))
Base.RefValue{Task}(Task (runnable) @0x000000010d944230)

julia> t[]
Task (runnable) @0x000000010d944230

Note: if an actor is on a worker process (pid > 1), you cannot get access to its Task. Instead you will get a string representation of it.

about a failed actor

If an actor fails, info will return the failed Task, which shows a clickable stack-trace in the REPL:

julia> send(myactor, :boom)
(:boom,)

julia> info(myactor)
Task (failed) @0x000000010d944230
MethodError: objects of type Symbol are not callable
Stacktrace:
 [1] myBehavior(::Link{Channel{Any}}, ::Symbol)
....

julia> typeof(ans)
Task

We can get the same information from the Ref{Task}-variable, we created earlier:

julia> t
Base.RefValue{Task}(Task (failed) @0x000000010d944230)

julia> t[]
Task (failed) @0x000000010d944230
MethodError: objects of type Symbol are not callable
Stacktrace:
 [1] myBehavior(::Link{Channel{Any}}, ::Symbol)
....

If a monitored or supervised actor has failed, you can get the failed task by using Actors.diag with the :err argument from the monitor or supervisor.

about actor state

For diagnostic purposes it is possible to get access to an actor's state by using Actors.diag. See also Diagnostics.

about an actor system

You can get further informations about registered or supervised actors: