RabbitMQ BasicConsume and Event Driven Issues relating to Console.ReadLine()

问题

The program below is basically the program from Receiver/Worker program from the C# Rabbit MQ Tutorial here: https://www.rabbitmq.com/tutorials/tutorial-two-dotnet.html (with a counter added).

There are two or three things that have me stumped about it:

1) If I comment out the "Console.ReadLine()" it consumes the messages from the Queue and displays:

Start 
Press [enter] to exit. 
My End - CountMessagesProcessed=0

The first few times I was testing, I couldn't figure out what was going on.

2) This line never shows up in the output: Console.WriteLine(" Press [enter] to exit.");. Presumably because it's before the "Console.ReadLine();", but why? What is the interplay between the ReadLine event and the BasicConsumer?

3) The MQ Tutorial page says to use CNTL-C to stop the "listener" process, but I find that just pressing enter works equally well.

I've written listeners for MQSeries before, with threading, which I might like better, but just trying to understand the basic tutorials provided.

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading.Tasks;
using RabbitMQ.Client;
using RabbitMQ.Client.Events;

namespace RabbitMQReceiver
{
    class Receive
    {
        public static void Main(string[] args)
        {
            var factory = new ConnectionFactory() { HostName = "localhost" };
            var myQueuename = "MyQueueName1";
            Console.WriteLine("My Start");


            using (var connection = factory.CreateConnection())
            using (var channel = connection.CreateModel())
            {
                channel.QueueDeclare(queue: myQueuename,
                                     durable: false,
                                     exclusive: false,
                                     autoDelete: false,
                                     arguments: null);

                var consumer = new EventingBasicConsumer(channel);
                int countMessagesProcessed = 0;

                // this chunk of code is passed as parm/variable to BasicConsume Method below to process each item pulled of the Queue 
                consumer.Received += (model, ea) =>
                {
                    var body = ea.Body;
                    var message = Encoding.UTF8.GetString(body);
                    countMessagesProcessed++;
                    Console.WriteLine(" [x] Received {0}", message);
                }

                channel.BasicConsume(queue: myQueuename,
                                     noAck: true,
                                     consumer: consumer);

                Console.WriteLine(" Press [enter] to exit.");  // this line never shows up in output 
                Console.ReadLine();    // if this line is commented out the message are consumed, but no Console.WriteLines appear at all. 
                Console.WriteLine("My End - CountMessagesProcessed=" + countMessagesProcessed);

            }
        }
    }
}

回答1:

Console.ReadLine() halts execution of your program at that point while waiting for input, which allows the threads RabbitMQ is using to run in the meantime. Commented out, program execution runs to the end and exits, including the RabbitMQ threads.

Yes, you can type anything and it will halt execution of the program; once you hit the key, program execution will continue and run to the end.

来源：https://stackoverflow.com/questions/37192346/rabbitmq-basicconsume-and-event-driven-issues-relating-to-console-readline