如何在F#中的群集配置中创建参与者

Question

我正在用Akka.Cluster创建一个有三个节点A、B和C的示例，其中A是灯塔。到目前为止，从日志中看，当没有参与者或参与者是本地的(用spawn和spawnOpt创建)时，集群可以正常工作。我想从B中创建一个演员，然后从C中获得它。

使用

let _ = spawne system "r-actor" <@ actorOf (fun msg -> printfn "Received: %s" msg) @> []

我得到了

2016-08-31 01:59:00.1185|INFO|Akka.Actor.EmptyLocalActorRef|Message String from akka://calculatorSystem/deadLetters to akka://calculatorSystem/user/r-actor was not delivered. 1 dead letters encountered.

使用

let r = FromConfig.Instance :> RouterConfig |> SpawnOption.Router
let _ = spawne system "r-actor" <@ actorOf (fun msg -> printfn "Received: %s" msg) @> [r]

抛出异常

Akka.Configuration.ConfigurationException类型的未处理异常发生在Akka.dll中 附加信息：Configuration problem while creating [akka://calculatorSystem/user/r-actor] with router dispatcher [akka.actor.default-dispatcher] and mailbox and routee dispatcher [akka.actor.default-dispatcher] and mailbox [].

Node C上的测试函数是

let rec calculate content =
  printfn "Processing %s" content
  let actor = select "/user/r-actor" system
  actor <! content
  let text = Console.ReadLine()
  if text <> "quit" then
    calculate text
calculate "sample1"

HOCON (节点B)

    akka {
      actor {
        provider = "Akka.Cluster.ClusterActorRefProvider, Akka.Cluster"
        serializers {
          wire = "Akka.Serialization.WireSerializer, Akka.Serialization.Wire"
        }
        serialization-bindings {
          "System.Object" = wire
        }
        deployment {
          /user/add {
            router = round-robin-pool
            nr-of-instances = 10
            cluster {
              enabled = on
              max-nr-of-instances-per-node = 10
              allow-local-routees = off
            }
          }
          /user/r-actor {
            router = round-robin-pool
            nr-of-instances = 10
            cluster {
              enabled = on
              max-nr-of-instances-per-node = 10
              allow-local-routees = off
            }
          }
        }
      }
      remote {
        log-remote-lifecycle-events = DEBUG
        log-received-messages = on
        helios.tcp {
          transport-class = "Akka.Remote.Transport.Helios.HeliosTcpTransport, Akka.Remote"
          applied-adapters = []
          transport-protocol = tcp
          hostname = "127.0.0.1"
          port = 0
        }
      }
      loggers = ["Akka.Logger.NLog.NLogLogger,Akka.Logger.NLog"]
      cluster {
        seed-nodes = [
          "akka.tcp://calculatorSystem@127.0.0.1:7001"
        ]
        roles = ["add-service"]
        auto-down-unreachable-after = 10s
      }
    }

如何创建一个可以由集群中的另一个节点调用的参与者？

Answer 1

定义路由器配置时，不要使用/user前缀-它是自动添加的。

另外，如果您想选择驻留在另一个节点上的参与者，您需要使用完整的参与者路径(带有节点地址)--这是因为事实上，可能有不同的参与者生活在不同的节点上，具有相同的路径。你必须精确。

通常，在编译时，您不会知道节点的地址。提取它的方法有两种：

1.从群集状态获取地址

这比较容易，但您正在失去加入/离开节点的反应能力。你每次都要检查它，这很慢。本例使用ActorSelection.ResolveOne检索实际的IActorRef实例。

async {
    let members = Cluster.Get(system).State.Members
    let actorRefs =
        members 
        |> Seq.filter (fun m -> m.Roles.Contains("expected")) // use roles to filter out nodes that shouldn't be checked
        |> Seq.map (fun m -> 
            let selection = select (m.Address.ToString() + "user/r-actor") system
            let actorRef = selection.ResolveOne(timeout) |> Async.AwaitTask)
        |> Async.Parallel }

2.订阅群集事件并对连接/离开节点作出反应

在这里，您可以在节点加入/离开时对它们作出反应。它还使用Identify/ActorIdentity来接收实际的IActorRef，这是更快的选项。

let aref =  
    spawn system "listener"
    <| fun mailbox ->
        let cluster = Cluster.Get (mailbox.Context.System)
        cluster.Subscribe (mailbox.Self, [| typeof<ClusterEvent.IMemberEvent> |])
        mailbox.Defer <| fun () -> cluster.Unsubscribe (mailbox.Self)
        let rec loop () = 
            actor {
                let! (msg: obj) = mailbox.Receive ()
                match msg with
                | :? ClusterEvent.MemberUp as up -> 
                    // new node joined the cluster
                    let selection = select (up.Member.Address.ToString() + "user/r-actor") mailbox
                    selection <! Identify(null) // request actor under selection to identify itself
                | :? ActorIdentity as id when id.Subject <> null ->
                    // actor has identified itself
                    id.Subject <! "hello"
                | :? ClusterEvent.MemberRemoved as rem -> 
                    //  node leaved the cluster, invalidate all actors from that node
                | _ -> ()
                return! loop () }
        loop ()

如果有疑问，我编写了一个关于从博客帖子创建Akka.NET集群的F#。也许你会发现它很有用。