Mac OS不提供epoll方法，本机测试的话用kqueue

Check for epoll.java

final boolean isMac = 
  System.getProperty("os.name").toLowerCase(Locale.US).contains("mac");
    // Configure the server.
    // See https://netty.io/wiki/native-transports.html
    EventLoopGroup bossGroup;
    EventLoopGroup workerGroup;
    if (isMac) {
        bossGroup = new io.netty.channel.kqueue.KQueueEventLoopGroup();
        workerGroup = new io.netty.channel.kqueue.KQueueEventLoopGroup(5);
    } else {
        bossGroup =  new io.netty.channel.epoll.EpollEventLoopGroup();
        workerGroup = new io.netty.channel.epoll.EpollEventLoopGroup(5);
    }