Concurrency 用Clojure进行服务器编程

如何在Clojure中实现10k连接echo服务器

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clojure.contrib.server-socket不是答案，因为它为每个连接包装了一个新的操作系统线程。

clojure的好处是，您拥有所有这些适用于JVM的优秀库，它们都经过了高度优化、可配置和深思熟虑。像这样的事情应该会让你行动起来：

(ns netty
  (:gen-class)
  (:import
     [java.net InetSocketAddress]
     [java.util.concurrent Executors]
     [org.jboss.netty.bootstrap ServerBootstrap]
     [org.jboss.netty.channel Channels ChannelPipelineFactory
                              SimpleChannelHandler]
     [org.jboss.netty.channel.socket.nio NioServerSocketChannelFactory]
     [org.jboss.netty.buffer ChannelBuffers]))

(declare make-handler)

(defn start
  "Start a Netty server. Returns the pipeline."
  [port handler]
  (let [channel-factory (NioServerSocketChannelFactory.
                          (Executors/newCachedThreadPool)
                          (Executors/newCachedThreadPool))
        bootstrap (ServerBootstrap. channel-factory)
        pipeline (.getPipeline bootstrap)]
    (.addLast pipeline "handler" (make-handler))
    (.setOption bootstrap "child.tcpNoDelay", true)
    (.setOption bootstrap "child.keepAlive", true)
    (.bind bootstrap (InetSocketAddress. port))
    pipeline))

(defn make-handler
  "Returns a Netty handler."
  []
  (proxy [SimpleChannelHandler] []
    (channelConnected [ctx e]
      (let [c (.getChannel e)]
        (println "Connected:" c)))

    (channelDisconnected [ctx e]
      (let [c (.getChannel e)]
        (println "Disconnected:" c)))

    (messageReceived [ctx e]
      (let [c (.getChannel e)
            cb (.getMessage e)
            msg (.toString cb "UTF-8")]
        (println "Message:" msg "from" c)))

    (exceptionCaught
      [ctx e]
      (let [throwable (.getCause e)]
        (println "@exceptionCaught" throwable))
      (-> e .getChannel .close))))

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您是指c10k问题吗？我读过，是的，我很好奇如何用这种有趣的语言实现它。请注意，clojure大量宣传其并发功能。谢谢！我在这里提出了一个简单的leiningen项目：如何向该服务器发送消息？@vemv我已经更新了repo，使用github项目使用公共netty，并添加了如何向服务器发送消息的示例。