为什么在客户机被Sigkill杀死时调用服务器上的channelInactive？

Question

有一个echo服务器和一个echo客户端。当我使用kill-9 杀死客户端进程时，将调用服务器上的channelinactive。

EchoServer类

public class EchoServer {
  private final int port;

  public EchoServer(int port) {
    this.port = port;
  }

  public static void main(String[] args) throws InterruptedException {
    int port = 9001;
    new EchoServer(port).start();
  }

  public void start() throws InterruptedException {
    EventLoopGroup group = new NioEventLoopGroup();

    try {
      ServerBootstrap bootstrap = new ServerBootstrap();
      bootstrap
          .group(group)
          .channel(NioServerSocketChannel.class)
          .childHandler(new ChannelInitializer<SocketChannel>() {
            @Override
            protected void initChannel(SocketChannel ch) throws Exception {
              ch.pipeline()
                .addLast(new ChannelInboundHandlerAdapter() {
                  @Override
                  public void channelInactive(ChannelHandlerContext ctx) throws Exception {
                    System.out.println("channelInactive()");
                  }
                });
            }
          });

      ChannelFuture future = bootstrap.bind(new InetSocketAddress(port)).sync();
      future.channel().closeFuture().sync();
    } finally {
      group.shutdownGracefully().sync();
    }
  }
}

EchoClient类

public class EchoClient {
  private final String host;
  private final int port;

  public EchoClient(String host, int port) {
    this.host = host;
    this.port = port;
  }

  public void start() throws InterruptedException {
    EventLoopGroup group = new NioEventLoopGroup();
    try {
      Bootstrap bootstrap = new Bootstrap();
      bootstrap
          .group(group)
          .channel(NioSocketChannel.class)
          .handler(new ChannelInitializer<SocketChannel>() {
            @Override
            protected void initChannel(SocketChannel ch) throws Exception {
            }
          });

      ChannelFuture future = bootstrap.connect(new InetSocketAddress(host, port)).sync();
      future.channel().closeFuture().sync();
    } finally {
      group.shutdownGracefully().sync();
    }
  }

  public static void main(String[] args) throws InterruptedException {
    new EchoClient("localhost", 9001).start();
  }
}

Answer 1

客户端被SIGKILL杀死，因此它应该没有时间主动关闭这个套接字。

客户端应用程序不会主动关闭套接字。如果本地应用程序不再打开套接字，客户端OS内核将隐式关闭该套接字。