tcp - Netty:在多个 Netty 客户端之间共享 NioClientSocketChannelFactory 的正确方法是什么

Question

我是 Netty 的新手。我正在使用“Netty 3.6.2.Final”。我创建了一个 Netty 客户端 (MyClient)，它与远程服务器通信(该服务器实现了基于 TCP 的自定义协议(protocol))。我为每个 MyClient 实例(在构造函数中)创建一个新的 ClientBootstrap 实例。我的问题是，如果我在 MyClient 的所有实例之间共享“NioClientSocketChannelFactory”工厂对象，那么我何时/如何释放与“NioClientSocketChannelFactory”关联的所有资源？

换句话说，由于我的 Netty 客户端运行在一个 24x7 全天候运行的 JBOSS 容器中，我是否应该通过调用“bootstrap.releaseExternalResources();”来释放所有资源？我应该何时/何地这样做？

更多信息:我的 Netty 客户端是从 JBOSS 容器内的两个场景调用的。首先，在无限循环中，每次传递需要发送到远程服务器的字符串(效果类似于下面的代码)

for( ; ; ){
    //Prepare the stringToSend
    //Send a string and receive a string
String returnedString=new MyClient().handle(stringToSend);
}

另一种情况是我的 Netty Client 在并发线程中调用，每个线程调用“new MyClient().handle(stringToSend);”。

我在下面给出了框架代码。它与 Netty 网站上的 TelnetClient 示例非常相似。

我的客户

import org.jboss.netty.bootstrap.ClientBootstrap;
import org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory;
public class MyClient {
    //Instantiate this only once per application
    private final static Timer timer = new HashedWheelTimer();

    //All below must come from configuration
    private final String host ="127.0.0.1";
    private final int port =9699; 
    private final InetSocketAddress address = new InetSocketAddress(host, port);
    private ClientBootstrap bootstrap;

    //Timeout when the server sends nothing for n seconds.
        static final int READ_TIMEOUT = 5;

        public MyClient(){
            bootstrap = new ClientBootstrap(NioClientSocketFactorySingleton.getInstance());
        }

    public String handle(String messageToSend){
        bootstrap.setOption("connectTimeoutMillis", 20000);
            bootstrap.setOption("tcpNoDelay", true);
            bootstrap.setOption("keepAlive", true);
            bootstrap.setOption("remoteAddress", address);
        bootstrap.setPipelineFactory(new MyClientPipelineFactory(messageToSend,bootstrap,timer));

         // Start the connection attempt.
            ChannelFuture future = bootstrap.connect();

            // Wait until the connection attempt succeeds or fails.
            channel = future.awaitUninterruptibly().getChannel();


            if (!future.isSuccess()) { 
                return null;  
            }

            // Wait until the connection is closed or the connection attempt fails.
            channel.getCloseFuture().awaitUninterruptibly();

            MyClientHandler myClientHandler=(MyClientHandler)channel.getPipeline().getLast();
            String messageReceived=myClientHandler.getMessageReceived();
        return messageReceived;
    }
}

单例 NioClientSocketChannelFactory

public class NioClientSocketFactorySingleton {
private static NioClientSocketChannelFactory nioClientSocketChannelFactory;

private NioClientSocketFactorySingleton() {
}

public static synchronized NioClientSocketChannelFactory getInstance() {
    if ( nioClientSocketChannelFactory == null) {
        nioClientSocketChannelFactory=new NioClientSocketChannelFactory(
            Executors.newCachedThreadPool(),
            Executors.newCachedThreadPool());
    }
    return  nioClientSocketChannelFactory;
 }

  protected void finalize() throws Throwable {
    try{
    if(nioClientSocketChannelFactory!=null){    
        // Shut down thread pools to exit.
        nioClientSocketChannelFactory.releaseExternalResources();
    } 
    }catch(Exception e){
    //Can't do anything much
    }
  }
} 

我的客户管道工厂

public class MyClientPipelineFactory implements ChannelPipelineFactory {

    private String messageToSend;
    private ClientBootstrap bootstrap;
    private Timer timer;
    public MyClientPipelineFactory(){

    }
    public MyClientPipelineFactory(String messageToSend){
        this.messageToSend=messageToSend;
    }

    public MyClientPipelineFactory(String messageToSend,ClientBootstrap bootstrap, Timer timer){
        this.messageToSend=messageToSend;
        this.bootstrap=bootstrap;
        this.timer=timer;
    }

        public ChannelPipeline getPipeline() throws Exception {

            // Create a default pipeline implementation.
            ChannelPipeline pipeline = pipeline();

            // Add the text line codec combination first,
            //pipeline.addLast("framer", new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
            pipeline.addLast("decoder", new StringDecoder());
            pipeline.addLast("encoder", new StringEncoder());

            //Add readtimeout
            pipeline.addLast("timeout", new ReadTimeoutHandler(timer, MyClient.READ_TIMEOUT));

            // and then business logic.
            pipeline.addLast("handler", new MyClientHandler(messageToSend,bootstrap));


            return pipeline;
        }
}

我的客户端处理程序

public class MyClientHandler extends SimpleChannelUpstreamHandler { 

    private String messageToSend="";
    private String messageReceived="";


    public MyClientHandler(String messageToSend,ClientBootstrap bootstrap) {
        this.messageToSend=messageToSend;
        this.bootstrap=bootstrap;
    }

    @Override
    public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e){
        e.getChannel().write(messageToSend);
    }

    @Override
    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e){
        messageReceived=e.getMessage().toString();
    //This take the control back to the MyClient
    e.getChannel().close();
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) {
        // Close the connection when an exception is raised.
        e.getChannel().close();

    }


}

Answer 1

只有在确定不再需要 releaseExternalResources() 时才应调用它。例如，当应用程序停止或取消部署时。