Akka集群经典分布式发布订阅无法跨微服务接收消息问题排查求助

大家好，我最近在做Akka集群的跨微服务消息发布订阅，遇到了一个棘手的问题：我在微服务A里通过SenderActor使用Akka的**经典分布式发布订阅（Cluster Distributed Pub/Sub）**机制向content主题发送消息，但微服务B里的ReceiverActor始终收不到这条消息，想请各位帮忙分析下可能的原因。

以下是我的代码和配置细节：

微服务A相关配置与代码 #

application.conf配置 #

akka {
  actor {
    provider = "cluster"
  }
  remote {
    artery {
      enabled = on
      canonical {
        hostname = "localhost"
        port = 2551
      }
    }
  }
  cluster {
    seed-nodes = [
      "akka://cluster-system@localhost:2551"
    ]
  }
}

SenderActor实现 #

public class SenderActor extends AbstractActor {

  ActorRef mediator = DistributedPubSub.get(getContext().system()).mediator();

  @Override
  public Receive createReceive() {
    return receiveBuilder()
        .match(
            String.class,
            in -> {
              String out = in.toUpperCase();
              mediator.tell(new DistributedPubSubMediator.Publish("content", out), getSelf());
            })
        .build();
  }
}

微服务A主方法 #

public static void main(String[] args) {
  SpringApplication.run(MicroserviceAaApplication.class, args);
  Config config = ConfigFactory.load("application.conf");
  ActorSystem system = ActorSystem.create("cluster-system", config);
  Cluster cluster = Cluster.get(system);
  ActorRef publisher = system.actorOf(Props.create(SenderActor.class), "publisher");
  publisher.tell("hello from microservice A ", null);
}

微服务B相关配置与代码 #

application.conf配置 #

akka {
  actor {
    provider = "cluster"
  }
  remote {
    artery {
      enabled = on
      canonical {
        hostname = "localhost"
        port = 2552
      }
    }
  }
  cluster {
    seed-nodes = [
      "akka://cluster-system@localhost:2551"
    ]
  }
}

ReceiverActor实现 #

public class ReceiverActor extends AbstractActor {

  LoggingAdapter log = Logging.getLogger(getContext().system(), this);

  public ReceiverActor() {
    ActorRef mediator = DistributedPubSub.get(getContext().system()).mediator();
    mediator.tell(new DistributedPubSubMediator.Subscribe("content", getSelf()), getSelf());
  }

  @Override
  public Receive createReceive() {
    return receiveBuilder()
        .match(String.class, msg -> {
          log.info("Received message in receiver-actor-b: {}", msg);
        })
        .match(DistributedPubSubMediator.SubscribeAck.class,
            msg -> log.info("SubscribeAck: {}", msg))
        .build();
  }
}

微服务B主方法 #

public static void main(String[] args) {
  SpringApplication.run(MicroserviceBbApplication.class, args);
  Config config = ConfigFactory.load("application.conf");
  ActorSystem system = ActorSystem.create("cluster-system", config);
  Cluster cluster = Cluster.get(system);
  ActorRef subscriber = system.actorOf(Props.create(ReceiverActor.class), "subscriber");
}

问题现象 #

我在微服务A里发送了消息hello from microservice A ，但微服务B的日志里只显示了订阅成功的确认信息，没有收到实际的消息内容。微服务B的日志如下：

2023-08-20T15:53:14.067+02:00  INFO 7788 --- [           main] c.e.M.MicroserviceBbApplication          : Started MicroserviceBbApplication in 0.909 seconds (process running for 1.723)
2023-08-20T15:53:14.552+02:00  INFO 7788 --- [lt-dispatcher-5] akka.event.slf4j.Slf4jLogger             : Slf4jLogger started
2023-08-20T15:53:14.900+02:00  INFO 7788 --- [lt-dispatcher-5] akka.remote.artery.ArteryTransport       : Remoting started with transport [Artery tcp]; listening on address [akka://cluster-system@localhost:2552] with UID [6730186213375081245]
2023-08-20T15:53:14.925+02:00  INFO 7788 --- [lt-dispatcher-5] akka.cluster.Cluster                     : Cluster Node [akka://cluster-system@localhost:2552] - Starting up, Akka version [2.8.3] ...
2023-08-20T15:53:14.980+02:00  INFO 7788 --- [lt-dispatcher-5] akka.cluster.Cluster                     : Cluster Node [akka://cluster-system@localhost:2552] - Registered cluster JMX MBean [akka:type=Cluster]
2023-08-20T15:53:14.981+02:00  INFO 7788 --- [lt-dispatcher-5] akka.cluster.Cluster                     : Cluster Node [akka://cluster-system@localhost:2552] - Started up successfully
2023-08-20T15:53:15.006+02:00  INFO 7788 --- [t-dispatcher-13] akka.cluster.Cluster                     : Cluster Node [akka://cluster-system@localhost:2552] - No downing-provider-class configured, manual cluster downing required, see https://doc.akka.io/docs/akka/current/typed/cluster.html#downing
2023-08-20T15:53:15.624+02:00  INFO 7788 --- [t-dispatcher-13] akka.cluster.Cluster                     : Cluster Node [akka://cluster-system@localhost:2552] - Received InitJoinAck message from [Actor[akka://cluster-system@localhost:2551/system/cluster/core/daemon#1745370250]] to [akka://cluster-system@localhost:2552]
2023-08-20T15:53:15.675+02:00  INFO 7788 --- [t-dispatcher-13] akka.cluster.Cluster                     : Cluster Node [akka://cluster-system@localhost:2552] - Welcome from [akka://cluster-system@localhost:2551]
2023-08-20T15:53:16.077+02:00  INFO 7788 --- [lt-dispatcher-5] c.example.MicroserviceBB.ReceiverActor   : SubscribeAck: SubscribeAck(Subscribe(content,None,Actor[akka://cluster-system/user/subscriber1#-339648796]))
2023-08-20T16:24:19.549+02:00  INFO 7788 --- [t-dispatcher-40] akka.actor.CoordinatedShutdown           : Running CoordinatedShutdown with reason [JvmExitReason]
Process finished with exit code 130

从日志能看到集群已经成功建立连接，订阅也确认了，但就是收不到消息，有没有大佬能帮我找找问题出在哪？

备注：内容来源于stack exchange，提问作者Bashir Hussein