NIO 多路复用多线程版

服务端代码：

import lombok.extern.slf4j.Slf4j;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;
import java.util.concurrent.ConcurrentlinkedDeque;
import java.util.concurrent.atomic.AtomicInteger;

import static com.netty.c1.ByteBufferUtil.debugAll;


@Slf4j
public class MultiThreadServer {

    public static void main(String[] args) throws IOException {
        Thread.currentThread().setName("boss");
        Selector boss = Selector.open();
        ServerSocketChannel ssc = ServerSocketChannel.open();
        ssc.configureBlocking(false);
        ssc.register(boss, SelectionKey.OP_ACCEPT, null);
        ssc.bind(new InetSocketAddress(8080));
        // 创建固定数量的 worker 并初始化
        // 注意如果代码跑在docker中，不是获取docker中的cpu数量，还是物理机的cpu数量
        // 该bug在jdk10以后修复了
        Worker[] workers = new Worker[Runtime.getRuntime().availableProcessors()];
        for (int i = 0; i < workers.length; ++i) {
            workers[i] = new Worker("worker-" + i);
        }

        AtomicInteger atomicInteger = new AtomicInteger();
        while (true) {
            boss.select();
            Iterator iter = boss.selectedKeys().iterator();
            while (iter.hasNext()) {
                SelectionKey key = iter.next();
                iter.remove();
                if (key.isAcceptable()) {
                    SocketChannel sc = ssc.accept();
                    sc.configureBlocking(false);
                    log.debug("connected...{}", sc.getRemoteAddress());
                    log.debug("before register...{}", sc.getRemoteAddress());
                    workers[atomicInteger.getAndIncrement()% workers.length].register(sc);
                    log.debug("after register...{}", sc.getRemoteAddress());
                }
            }
        }
    }

    static class Worker implements Runnable {

        private Thread thread;
        private Selector selector;
        private String name;
        private volatile boolean start = false; // 用来控制一个work对象只跟一个线程关联
        private ConcurrentlinkedDeque queue = new ConcurrentlinkedDeque<>(); //　用一个队列构建两个线程直接信息传递的通道

        public Worker(String name) {
            this.name = name;
        }

        public void register(SocketChannel sc) throws IOException {
            if(!start) {
                thread = new Thread(this, name);
                selector = Selector.open();
                thread.start();
                start = true;
            }
            // 向队列中添加了任务，但是任务还没有被执行
            queue.add(() ->{
                try {
                    sc.register(selector, SelectionKey.OP_READ, null);
                } catch (ClosedChannelException e) {
                    e.printStackTrace();
                }
            });
            selector.wakeup(); // 为了唤醒worker线程中的select()方法

        }

        @Override
        public void run() {
            while (true) {
                try {
                    selector.select();  // 有事件发生或者主动调用selector的wakeup方法，解除阻塞
                    Runnable task = queue.poll();
                    if (task != null) {
                        task.run();
                    }
                    Iterator iter = selector.selectedKeys().iterator();
                    while (iter.hasNext()) {
                        SelectionKey key = iter.next();
                        iter.remove();
                        if (key.isReadable()) {
                            ByteBuffer buffer = ByteBuffer.allocate(16);
                            SocketChannel channel = (SocketChannel) key.channel();
                            channel.read(buffer);
                            buffer.flip();
                            debugAll(buffer);
                        }
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

1. boos线程处理accept事件
2. worker线程处理 read 和 write事件
3. 事件发生在channel上