Distributed Akka talk

Slides from my talk at the Cross Functional Amsterdam meetup

Transcript

1. ‘Distributed Akka’ @RayRoestenburg Friday, October 11, 13
2. My “Am I going to use this?” rules Must be open source. The code quality must be excellent. Must be able to test ‘everything’ relatively easily. Docs must be comprehensive. Must have examples. The creators / community must have social skills. Pull request litmus test. Friday, October 11, 13
3. Actor Model message passing safely mutate state create send/receive become Friday, October 11, 13
4. Akka Actors Stable IDs (ActorRef) Message ordering sender / receiver pair Configurable Dispatchers ActorSystems ActorPaths Parental Supervision Friday, October 11, 13
5. JVM Shared heap (no preemption) Immutability not enforced Reuse Java libraries Performance Friday, October 11, 13
6. master worker “user” guardian loadgen “loadgen” ActorSystem Friday, October 11, 13
7. master worker “user” guardian /user/master/worker akka://loadgen/user/master/worker loadgen Actor Paths Friday, October 11, 13
8. master worker “user” guardian path from worker to worker1: ../worker1 loadgen worker1 Friday, October 11, 13
9. master worker “user” guardian Guardian is parent of master, master parent of worker. loadgen Friday, October 11, 13
10. master worker “user” guardian Guardian supervises master, master supervises of worker. loadgen Friday, October 11, 13
11. master worker “user” guardian Watch loadgen worker Friday, October 11, 13
12. master worker “user” guardian Stop / Resume / Escalate / Restart loadgen Friday, October 11, 13
13. master worker1 “user” guardian akka.tcp://loadgen@host:port/user/master/worker loadgen akka.tcp Friday, October 11, 13
14. master worker1 “user” guardian akka.tcp://loadgen@host:port/user/master/worker loadgen akka.tcp Java Serialization By Default (Other Options) Friday, October 11, 13
15. master worker1 “user” guardian akka.udp://loadgen@host:port/user/master/worker loadgen akka.tcp Pluggable transports akka.udp Friday, October 11, 13
16. Membership Partition work Partition state Resilience Friday, October 11, 13
17. Membership Partition work Partition state Resilience Friday, October 11, 13
18. Static vs Dynamic (a,b,c) (x) (x) (x) c b d join a leave x a b c Friday, October 11, 13
19. (a,b,c) (x) (x) (x) x a b c Static membership pre-configured nodes Startup sequence? restart after failure? Friday, October 11, 13
20. Remote Lookup / Deploy ActorRefs Friday, October 11, 13
21. REPL: Lookup Friday, October 11, 13
22. master worker loadgen user runner loadrun /user/runner/master/worker Remote Deployment user /runner/master/worker { remote = "akka.tcp://loadgen@host:port" } Friday, October 11, 13
23. master worker loadgen user runner loadrun loadgen@host:port/user/master/worker Remote Lookup user Friday, October 11, 13
24. master worker loadgen user runner loadrun /user/runner/master/worker user /scenario/master/worker { remote = "akka.tcp://loadgen@host:2552" } What if loadgen node is not up? Friday, October 11, 13
25. ActorRef ActorSelection ActorIdentity Friday, October 11, 13
26. ActorSelection ! only Friday, October 11, 13
27. val selection = context.actorSelection(path) selection ! msg Friday, October 11, 13
28. val future = context.actorSelection(path) .resolveOne future.map( aRef => aRef ! msg).recover { case ActorNotFound(selection) => //ouch } Friday, October 11, 13
29. ActorIdentity message contains an ActorRef Friday, October 11, 13
30. identify active lookup runner master worker In between lookup actor identifies remote actor Friday, October 11, 13
31. def receive = identify def identify:Receive = { // do identification of ActorRef } def active(actor:ActorRef) : Receive = { // forward messages when active // or become(identify) when actor is terminated } Lookup Actor Friday, October 11, 13
32. context.setReceiveTimeout(timeout) sendIdentifyRequest() def identify:Receive = { case ReceiveTimeout => sendIdentifyRequest // .. more to follow } def sendIdentifyRequest(): Unit = { val selection = context.actorSelection(path) selection ! Identify(path) } Friday, October 11, 13
33. def identify: Receive = { case ActorIdentity(`path`, Some(actor)) => context.setReceiveTimeout(Undefined) context.become(active(actor)) context.watch(actor) case ActorIdentity(`path`, None) => // not found case ReceiveTimeout => sendIdentifyRequest() case msg:Any => // ignore } Friday, October 11, 13
34. def active(actor: ActorRef): Receive = { case Terminated(actorRef) => context.become(identify) context.setReceiveTimeout(3 seconds) sendIdentifyRequest() case msg:Any => actor forward msg } Friday, October 11, 13
35. deploying maybe active deploy runner master worker Similar for RemoteDeploy Friday, October 11, 13
36. def receive = deploying def deploying:Receive = { case ReceiveTimeout => deployAndWatch() case msg:Any => // ignore } def maybeActive(actor:ActorRef): Receive = { case Terminated(actorRef) => context.become(deploying) context.setReceiveTimeout(3 seconds) deployAndWatch() case msg:Any => actor forward msg } Similar for a RemoteDeploy Friday, October 11, 13
37. Dynamic membership Friday, October 11, 13
38. Cluster c b d join a leave Friday, October 11, 13
39. Gossip Protocol c b d join a leave Friday, October 11, 13
40. Seed nodes • initial contact points, joins automatically • no seed nodes: join programmatically or through cluster admin • bin/akka-cluster <node-hostname> <jmx- port> <command> Friday, October 11, 13
41. val cluster = Cluster(actorSystem) cluster.join(address) cluster.leave(address) Cluster(system).subscribe(clusterListener, classOf[MemberUp]) (watch also works as expected) Programmatically join and leave Friday, October 11, 13
42. akka { actor { provider = "akka.cluster.ClusterActorRefProvider" } cluster { seed-nodes = [ "akka.tcp://loadgen@127.0.0.1:2551"] roles = ["loadrun", “loadgen”] auto-down = on } } Friday, October 11, 13
43. Partition Work Friday, October 11, 13
44. Routers Broadcast RoundRobin AdaptiveLoadBalancing Friday, October 11, 13
45. Routers val broadcast = context.actorOf( Props[BoxOffice].withRouter( ClusterRouterConfig(BroadcastRouter(), ClusterRouterSettings(10000,"/user/ worker",false,Some("workerRouter"))) ) ) Friday, October 11, 13
46. Partition State Friday, October 11, 13
47. def createWorkerRef:ActorRef = { import ConsistentHashingRouter._ def hashMapping: ConsistentHashMapping = { case DoWork(id, _) 㱺 id } clusterRouterConfig = ClusterRouterConfig(ConsistentHashingRouter( hashMapping = hashMapping, nrOfInstances = 1000) routerSettings = ClusterRouterSettings(10000,"/user/boxOffice",false,Some("boxOffice")))) context.actorOf(Props[Worker].withRouter(clusterRouterConfig, routerSettings) } Create a Consistently hashed worker Friday, October 11, 13
48. Resilience Friday, October 11, 13
49. Remote DeathWatch Cluster Death Watch Supervision of Remotely deployed actors Friday, October 11, 13
50. context.watch(actor) def receive = { case Terminated(`ref`) => //take action } Friday, October 11, 13