@Configuration
public static class ReactNettyConfiguration {
    @Bean
    public ReactorResourceFactory reactorClientResourceFactory() {
        System.setProperty("reactor.netty.ioSelectCount","1");
        // 這里工作線程數(shù)為2-4倍都可以。看具體情況
        int ioWorkerCount = Math.max(Runtime.getRuntime().availableProcessors()*3, 4));
        System.setProperty("reactor.netty.ioWorkerCount",String.valueOf(ioWorkerCount);
        return new ReactorResourceFactory();
    }
}

package reactor.netty.resources;
import io.netty.channel.Channel;
import io.netty.channel.EventLoopGroup;
import java.time.Duration;
import java.util.Objects;
import reactor.core.Disposable;
import reactor.core.publisher.Mono;
@FunctionalInterface
public interface LoopResources extends Disposable {
    // 這里是worker線程數(shù)，未配置的話。從cpu核心數(shù)和4直接取一個大的
    int DEFAULT_IO_WORKER_COUNT = Integer.parseInt(System.getProperty("reactor.netty.ioWorkerCount", "" + Math.max(Runtime.getRuntime().availableProcessors(), 4)));
    // 這里是select線程數(shù) 默認是-1
    int DEFAULT_IO_SELECT_COUNT = Integer.parseInt(System.getProperty("reactor.netty.ioSelectCount", "-1"));
    ....
    // 創(chuàng)建一個默認的資源，把兩個線程數(shù)的參數(shù)傳遞過去
    static LoopResources create(String prefix) {
        if (Objects.requireNonNull(prefix, "prefix").isEmpty()) {
            throw new IllegalArgumentException("Cannot use empty prefix");
        }
        return new DefaultLoopResources(prefix, DEFAULT_IO_SELECT_COUNT, DEFAULT_IO_WORKER_COUNT, true);
    }
    ....

DefaultLoopResources(String prefix, int selectCount, int workerCount, boolean daemon) {
        this.running = new AtomicBoolean(true);
        this.daemon = daemon;
        this.workerCount = workerCount;
        this.prefix = prefix;
        this.serverLoops = new AtomicReference<>();
        this.clientLoops = new AtomicReference<>();
        this.cacheNativeClientLoops = new AtomicReference<>();
        this.cacheNativeServerLoops = new AtomicReference<>();
        // 因為默認沒有配置 所以selectCode必然是-1
        if (selectCount == -1) {
            this.selectCount = workerCount;
            // serverSelectLoops沒有創(chuàng)建，而是直接使用的serverLoops
            this.serverSelectLoops = this.serverLoops;
            this.cacheNativeSelectLoops = this.cacheNativeServerLoops;
        }
        else {
            this.selectCount = selectCount;
            this.serverSelectLoops = new AtomicReference<>();
            this.cacheNativeSelectLoops = new AtomicReference<>();
        }
    }
    @SuppressWarnings("FutureReturnValueIgnored")
    EventLoopGroup cacheNioSelectLoops() {
        // 兩個相等的話 使用 cacheNioServerLoops 返回工作組
        if (serverSelectLoops == serverLoops) {
            return cacheNioServerLoops();
        }
        EventLoopGroup eventLoopGroup = serverSelectLoops.get();
        if (null == eventLoopGroup) {
            EventLoopGroup newEventLoopGroup = new NioEventLoopGroup(selectCount,
                    threadFactory(this, "select-nio"));
            if (!serverSelectLoops.compareAndSet(null, newEventLoopGroup)) {
                //"FutureReturnValueIgnored" this is deliberate
                newEventLoopGroup.shutdownGracefully(0, 0, TimeUnit.MILLISECONDS);
            }
            eventLoopGroup = cacheNioSelectLoops();
        }
        return eventLoopGroup;
    }
    // 這里相當于返回了工作組
    @SuppressWarnings("FutureReturnValueIgnored")
    EventLoopGroup cacheNioServerLoops() {
        EventLoopGroup eventLoopGroup = serverLoops.get();
        if (null == eventLoopGroup) {
            EventLoopGroup newEventLoopGroup = new NioEventLoopGroup(workerCount,
                    threadFactory(this, "nio"));
            if (!serverLoops.compareAndSet(null, newEventLoopGroup)) {
                //"FutureReturnValueIgnored" this is deliberate
                newEventLoopGroup.shutdownGracefully(0, 0, TimeUnit.MILLISECONDS);
            }
            eventLoopGroup = cacheNioServerLoops();
        }
        return eventLoopGroup;
    }