public async Task AAA() {
            var channel = Channel.CreateUnbounded<string>(new UnboundedChannelOptions() {  //创建一个无限容量的channel 
                SingleWriter = true, //网上说能限制多个生成者，但是实际没起作用
                SingleReader = true,  //如果只有一个消费者，设置为true后能避免读取加锁
            });
            var task1 = Task.Run(async () => { //启用一个异步线程，不停的生产数据
                while (true) {
                    var val = "1-" + Guid.NewGuid().ToString("N");
                    Console.WriteLine("生产者1:" + val);
                    await channel.Writer.WriteAsync(val);
                    await Task.Delay(1000);
                }
            });
            var task2 = Task.Run(async () => { //启用一个线程，不停的消费数据
                while (await channel.Reader.WaitToReadAsync()) { //阻塞等待数据
                    var val = await channel.Reader.ReadAsync();
                    Console.WriteLine("消费:" + val);
                }
            });
            while (true) { //可以多个生成者，当然也可以多个消费者
                var val = "2-" + Guid.NewGuid().ToString("N");
                Console.WriteLine("生产者2:" + val);
                await channel.Writer.WriteAsync(val);
                await Task.Delay(1000);
            }
        }
        public async Task BBB() {
            var channel = Channel.CreateBounded<int>(new BoundedChannelOptions(2) {  //创建一个指定容量的channel
                SingleWriter = true,
                SingleReader = true,
                Capacity = 4,  //容器容量，会覆盖BoundedChannelOptions构造传入容量，比如目前的4覆盖了上面的2
                //FullMode = BoundedChannelFullMode.DropWrite, //满了之后忽略要写入的项
                //FullMode = BoundedChannelFullMode.DropNewest, //满了之后删除最新项，预留空间
                //FullMode = BoundedChannelFullMode.Wait, //满了阻塞等待读取后腾出空间
                FullMode = BoundedChannelFullMode.DropOldest, //满了之后删除最旧项，留出空间
            });
            for (int i = 0; i < 5; i++) {
                await channel.Writer.WriteAsync(i);
            }
            while (await channel.Reader.WaitToReadAsync()) { //阻塞等待数据
                var val = await channel.Reader.ReadAsync();
                Console.WriteLine("消费:" + val); //输出:1,2,3,4
            }
        }