I have written a wrapper around RabbitMQ, and everything is working fine, too well actually, I am receiving messages quicker than I can process them. How do I limit how many messages I get from the queue or better, only consume and process one at a time?

public void Consume()
        {
            if (_channel != null)
            {
                // setup a listener for new messages
                var consumer = new EventingBasicConsumer(_channel);

                consumer.Received  = (model, ea) =>
                {
                    var body = ea.Body.ToArray();
                    var message = Encoding.UTF8.GetString(body);
                    var evt = new MessageEventArgs(body, message);

                    OnMessageReceived(evt);
                };

                _channel.BasicConsume(queue: _queue, autoAck: true, consumer: consumer);
            }
        }

CodePudding user response：

To limit the number of messages consumed from the queue or to only consume and process one message at a time, you can modify the Consume method in your RabbitMQ wrapper as follows:

1. Set the autoAck parameter of the BasicConsume method to false. This will disable automatic acknowledgement of messages, which means that the messages will remain in the queue until they are manually acknowledged.

2. Add a call to the BasicAck method in the Received event handler after the message has been processed. This will send an acknowledgement to RabbitMQ that the message has been successfully processed and can be removed from the queue.

   public void Consume()
   {
       if (_channel != null)
       {
           // setup a listener for new messages
           var consumer = new EventingBasicConsumer(_channel);
   
           consumer.Received  = (model, ea) =>
           {
               var body = ea.Body.ToArray();
               var message = Encoding.UTF8.GetString(body);
               var evt = new MessageEventArgs(body, message);
   
               OnMessageReceived(evt);
   
               // send acknowledgement to RabbitMQ that the message has been processed
               _channel.BasicAck(ea.DeliveryTag, false);
           };
   
           _channel.BasicConsume(queue: _queue, autoAck: false, consumer: consumer);
       }
   

   }

With these changes, the Consume method will only consume and process one message at a time, and the messages will remain in the queue until they are manually acknowledged.

CodePudding user response：

To limit the messages consumed

//limit to 5 messages
channel.BasicQos(0, 5, false);

After this you can call the BasicConsume method with noAck parameter to false.

channel.BasicConsume(queue: _queue, autoAck: false, consumer: consumer);