多路复用技术中的“多路”是什么意思？它与线程池有何关联？

import java.io.IOException;
import java.nio.channels.*;
import java.nio.ByteBuffer;
import java.util.Iterator;
import java.util.concurrent.*;

public class MultiplexedServer {
    private static final int PORT = 8080;
    private static final int THREAD_POOL_SIZE = 4;

    public static void main(String[] args) throws IOException {
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        serverSocketChannel.bind(new InetSocketAddress(PORT));
        serverSocketChannel.configureBlocking(false);

        ExecutorService threadPool = Executors.newFixedThreadPool(THREAD_POOL_SIZE);
        Selector selector = Selector.open();
        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

        while (true) {
            selector.select(); // 阻塞等待就绪的事件
            Iterator<SelectionKey> selectedKeys = selector.selectedKeys().iterator();
            while (selectedKeys.hasNext()) {
                SelectionKey key = selectedKeys.next();
                selectedKeys.remove();

                if (key.isAcceptable()) {
                    // 接受连接并注册到Selector上
                    SocketChannel clientChannel = serverSocketChannel.accept();
                    clientChannel.configureBlocking(false);
                    clientChannel.register(selector, SelectionKey.OP_READ);
                } else if (key.isReadable()) {
                    // 读取客户端数据并通过线程池处理
                    SocketChannel clientChannel = (SocketChannel) key.channel();
                    threadPool.submit(() -> handleClientData(clientChannel));
                }
            }
        }
    }

    private static void handleClientData(SocketChannel clientChannel) {
        try {
            ByteBuffer buffer = ByteBuffer.allocate(256);
            int bytesRead = clientChannel.read(buffer);
            if (bytesRead == -1) {
                clientChannel.close();
            } else {
                buffer.flip();
                // 处理数据
                System.out.println("Received data: " + new String(buffer.array(), 0, bytesRead));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}