So I'm testing RabbitMQ in one node. Plain and simple,
One producer sends messages to the queue,
Multiple consumers take tasks from that queue.
Currently consumers execute thousands of messages per second, they are too fast so I need them to slow down. Managing consumer-side throttling is not possible due to network unreliable nature.
Collectively consumers must not take more than 10 messages per second altogether from that queue.
Is there a way to configure RabbitMQ so as the queue dispatches a maximum of 10 messages per second?
If I remember correctly, once Rabbit MQ has delivered a message to the queue, it's up to consumers to consume a message. There are various consumers in different languages, you haven't mentioned anything specific, so I'm giving a generic answer.
In my understanding, you shouldn't try to impose any restrictions on Rabbit MQ itself, instead, consider implementing connection pool of message consumers that will be able to handle not more than X messages simultaneously on the client side. Alternatively, you can provide some kind of semaphore at the handler itself, but not on the Rabbit MQ server itself.
Related
If I have two queues from which I want to consume messages, and I use a single SimpleMessageQueueListenerContainer for it, in which order would the listeners be invoked/messages consumed when both queues have messages?
I will try to be more specific of the problem I am working on:
I have a consumer application which needs to consume messages from 2 queues – say regular-jobs-queue and infrequent-jobs-queue. If there are any messages in ‘infrequent-jobs-queue’ I want to consume those before consuming messages from ‘regular-jobs-queue’. I might not be able to combine these and put all messages into a single rabbitmq level priority queue and assign higher priority to infrequent-job message because of some upcoming use-cases like purging regular-jobs without affecting infrequent-jobs and others.
I am aware that RabbitMQ has support for consumer priority but I am not very sure if it will be applicable here. I want all instances of my consumer application to first consume messages of infrequent-jobs-queue if any and not prioritize amongst these consumers.
Or should I like have 2 containers, with dedicated consumer thread(s) per queue and have an internal priority-queue data structure into which I can put messages as and when consumed from rabbitmq queue.
Any help would be really appreciated. Thanks.
~Rashida
You can't do what you want; messages will be delivered with equal priority.
Moving them to an internal in-memory queue will risk message loss.
You might want to consider using one of the RabbitTemplate.receive() or receiveAndConvert() methods instead of a message-driven container.
That way you have complete control.
We're seeing an issue where consumers of our message queues are picking up messages from queues at the top of the alphabetical range. We have two applications: a producer, and a subscriber. We're using RabbitMQ 3.6.1.
Let's say that the message queues are setup like so:
Our first application, the producer, puts say 100 messages/second onto each queue:
Our second application, the subscriber, has five unique consumer methods that can deal with messages on each respective queue. Each method binds to it's respective queue. A subscriber has a prefetch of 1 meaning it can only hold one message at a time, regardless of queue. We may run numerous instances of the subscriber like so:
So the situation is thus: each queue is receiving 100 msg/sec, and we have four instances of subscriber consuming these messages, so each queue has four consumers. Let's say that the consumer methods can deal with 25 msg/sec each.
What happens is that instead of all the queues being consumed equally, the alphabetically higher queues instead get priority. It's seems as though when the subscriber becomes ready, RabbitMQ looks down the list of queues that this particular ready channel is bound to, and picks the first queue with pending messages.
In our situation, A_QUEUE will have every message consumed. B_QUEUE may have some consumed in certain race conditions, but C_QUEUE/D_QUEUE and especially E_QUEUE will rarely get touched.
If we turn off the publisher, the queues will eventually drain, top to bottom.
Is it possible to configure either RabbitMQ itself or possibly even the channel to use some sort of round robin distribution policy or maybe even random policy so that when a channel has numerous bound queues, all with messages pending, the distribution is even?
to clarify: you have a single subscriber application with multiple consumers in it, right?
I'm guessing you're using a single RabbitMQ Connection within the subscriber app.
Are you also re-using a single RabbitMQ Channel for all of your consumers? If so, that would be a problem. Be sure to use a new Channel for each consumer you start.
Maybe the picture is wrong, but if it's not then your setup is wrong. You don't need 4 queues if you are going to have subscribers that listen to each and every queue. You'd just need one queue, that has multiple instances of the same subscriber consuming from it.
Now to answer, yes (but no need to configure, as long as prefetch is 1), actually rabbitmq does distribute messages evenly. You can find about about that here, and on the same place actually how your setup should look like. Here is a quote from the link.
RabbitMQ just dispatches a message when the message enters the queue.
It doesn't look at the number of unacknowledged messages for a
consumer. It just blindly dispatches every n-th message to the n-th
consumer.
Is there any way in RabbitMQ to have multiple consumers get the same message from the same queue?
I need to send the same message to anyone who's listening but also ensure that someone deals with it. Basically, I need the fanout functionality of an exchange combined with the basic.ack functionality of a queue. Is there any way to accomplish this in a scalable way?
If you are trying to ensure that the message is properly processed, acknowledgement already provides this capability. If your consumer is unable to process the message and does not provide an ack it will be requeued and processed again by the next available consumer. Implementing multiple competing consumers on the same queue will give you round-robin delivery, allowing the other consumers a chance for success.
How scalable this will be depends on how long it takes to process each message compared to the incoming rate, queue durability, prefetch and how many competing consumers you have on the queue.
I am developing an app. and I am using activemq. Is there any way to do that one producer always send messages to one broker but on the opposite side there 3 consumers.Each consumer listens broker and can take any of message from queue.Is this possible?
I am using activemq for writing my app. logs to db.As u know writing logs to db is time taking process.That's why consumer is more and more slow than producer.For ex. I send 100.000 message(huge objects).Producer finishes sending messages in 20 mins.But When the producer finished, consumer has finished 4.000 message processing yet.
Yes, what you are describing is possible. In fact, you can have any number of consumers listening on a single queue. The messages are dispatched in a round-robin fashion between consumers.
What you should be aware of is that ActiveMQ performs much better sending small messages than large ones. If you need to send very large payloads (e.g. 100mb), you are far better off saving the message to a location that is accessible by both the producer and consumers (e.g. a network file system), and sending the location of the message instead. The consumer can then use that to read the message manually. This way you get a relatively small amount of traffic through the message broker.
I have two questions about RabbitMQ Work Queues:
As I understand it from the RabbitMQ tutorials, it seems that if I have a basic queue consumer client (just a basic "Hello, World!" consumer) and then I add a second consumer client for the same queue, then RabbitMQ will automatically dispatch the messages between those two queues in a round robin manner. Is that true (without adding in any extra configuration)?
My consumer clients are configured to only ever receive one message at a time, using (GetResponse response = channel.basicGet("my_queue", false). Since I am only ever receiving one message at a time, is it still necessary to set a prefetchCount (channel.basicQos(1)) for fair dispatch?
Answers to your questions:
Yes
No
However, your two questions 1 and 2 are not compatible. If you are using a consumer, it is designed to have messages pushed to it, and you don't use Basic.Get. When you use a consumer, you will need to use Basic.QoS to specify that the consumer can only "own" one unacknowledged message at a time. RabbitMQ will not push additional messages beyond the QoS limit.
Your alternative is to "pull" from the queue using Basic.Get, and you will control your own destiny as far as how many messages you run at a time.
Does this make sense?