问题可能是由于TCP）长连接上没有在规定时间内访问KeepAlive而导致的。为了解决此问题，可以在客户端或服务器端设置一个KeepAlive选项。

这里是使用Akka TCP实现TCP长连接的示例代码，其中使用了服务器端的KeepAlive选项：

import java.util.concurrent.TimeUnit
import akka.actor._
import akka.io._
import akka.io.Tcp._
import akka.util.ByteString
import scala.concurrent.duration._

object TCPServer extends App {
  implicit val system = ActorSystem()
  import system.dispatcher

  val endpoint = "localhost"
  val port = 8080

  val server = system.actorOf(Props[TcpServer], "tcp-server")

  IO(Tcp) ! Bind(server, new InetSocketAddress(endpoint, port))

  class TcpServer extends Actor with ActorLogging {

    def receive = {
      case b @ Bound(localAddress) =>
        log.info(s"Listening on $localAddress")

      case CommandFailed(_: Bind) =>
        log.error("Bind failed")
        context stop self

      case c @ Connected(remote, local) =>
        log.info(s"Accepted a new connection from $remote")

        val handler = context.actorOf(Props[TcpHandler])
        val connection = sender()
        connection ! Register(handler)

        context.watch(handler)

      case Terminated(handler) =>
        log.error(s"Terminating: $handler")
    }
  }

  class TcpHandler extends Actor with ActorLogging {
    context.setReceiveTimeout(30.seconds)

    def receive = {
      case Received(data) =>
        log.info(s"Received data: $data")

      case "close" =>
        log.info("Closing connection")
        sender() ! Close

      case _: ConnectionClosed =>
        log.info("Connection closed")
        context stop self

      case ReceiveTimeout =>
        log.info("No data received for 30 seconds")
        sender() ! Close
        context stop self
    }
  }
}

在此示例代码中，在TcpHandler Actor中设置了接收超时，如果在30秒钟内没有接收到数据，则会关闭连接并停止Actor进程。这个例子中，在接