RocketMQ NettyClientPublicExecutor_ 这个线程是做什么事情的？

处理客户端请求：接收客户端发来的请求，如获取Topic的路由信息、发送心跳等。
执行非阻塞操作：执行一些不会阻塞主业务流程的操作，例如异步的网络请求处理。

参考示例

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class RocketMQClient {

    private final String host;
    private final int port;
    private final ExecutorService publicExecutor;

    public RocketMQClient(String host, int port) {
        this.host = host;
        this.port = port;
        // 创建一个固定大小的线程池，用于处理公共任务
        this.publicExecutor = Executors.newFixedThreadPool(10);
    }

    public void start() throws Exception {
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(workerGroup)
             .channel(NioSocketChannel.class)
             .option(ChannelOption.SO_KEEPALIVE, true)
             .handler(new ChannelInitializer<SocketChannel>() {
                 @Override
                 protected void initChannel(SocketChannel ch) {
                     ch.pipeline().addLast(new StringDecoder(), new StringEncoder(),
                             new RocketMQClientHandler(publicExecutor));
                 }
             });

            Channel ch = b.connect(host, port).sync().channel();

            // 这里可以添加代码来发送和接收消息
            // ...

        } finally {
            workerGroup.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws Exception {
        RocketMQClient client = new RocketMQClient("localhost", 9876);
        client.start();
    }
}