I'm doing some research if rabbitMQ is the way to go for me.
Can I mix publish/subscribe and worker queues?
The goal is to have have a few queues which holds items of for specific process.
Each process can have a lot of workers.
The setup shown in this diagram is possible. If the exchange X is a direct or topic exchange, the 'specific process' would be represented by one of the two queues and routing of messages would be based on the routing key or topic of a message.
Consumers ('workers') would consume messages from the queues using round-robin.
Related
Two RabbitMQ clusters use two-way federation exchange to replicate messages, but how to achieve consume messages synchronously?
I use a consumer to consume messages in one cluster and messages in one cluster will be deleted, but in another cluster the messages are still there. How can I achieve that when I use a consumer to consume messages? In both two cluster the messages will be deleted.
Federation only copies messages, it does not copy actions on those messages. They will remain in the other cluster until they are consumed or deleted.
One option would be to set a message TTL for the other queue so that the messages will be automatically deleted after a certain period of time.
NOTE: the RabbitMQ team monitors the rabbitmq-users mailing list and only sometimes answers questions on StackOverflow.
I'm trying to scale-out a RabbitMQ messaging system. The current system is very simple - the producer sends a message to a fanout exchange and the message is handle by multiple consumers - classic fanout routing .
I have multiple consumers from different types (e.g: one that print to screen, one that logs to file, one that saves to DB,...).
My challenge - i'm not sure what's the best way to scale-out the consumers. If i add other consumers from the same type - i'll get double logs or double entries in the DB. ... (think about two DB consumers consuming from the same fanout exchange) .
I guess I can create a consumer that publish to a work-queue but I wonder if there's a better "builtin" solution in rabbitmq.
thanks in advance,
zf
If you need to scale consumers in order to consume faster all the messages coming from the fanout exchange you need competive consuming; so you need more consumers attached to the same queue bound to the fanout exchange.
In this way every consumer will consume a batch of messages indipendently from the others. The number of messages inside the batch is defined with the prefetch count property ( http://www.rabbitmq.com/consumer-prefetch.html ).
In this way, in your case, you should be able to scale consumers avoiding double logs and double entries in the DB.
all,
Background: now client produces many messages of different labels.Consumers may subscribe some labels of them(different consumer need different labels's msgs).
Now method: I used direct exchange in rabbitmq, consumer declared queue for itself, exchange distribute msgs to these queues.
Problem: there exsit many redundant msgs in queues which effects the performance.
A topic type in activemq supports user a method to distribute a msg to many subscribers, which need not creates large number queues for subscribers.
Does exsit a method in rabbitmq, or some suggestions to solve the problem?
I'm seeking some advise as to how best configure my rabbitMQ exchanges.
I'm trying to use a topic exchange in a round robin methodology. Each consumer has its own (uniquely) named queue attached to a topic exchange. I would like the exchange to round robin messages to each consumer queue for the "same" topic - lets say *.log for example.
I have tried multiple combinations and only seem to be able to simultaneously deliver messages to the consumer queues which effectively means I'm processing the message twice, once in each consumer.
For clarity I also have a fanout exchange, which I use to "control" the consumers (start, stop etc).this should remain in place in any outcome.
Any guidance on how best to achieve the stated outcome would be great.
Each consumer has its own (uniquely) named queue attached to a topic exchange
The trick is to have every worker/consumer that you want to round-robin between to setup a named queue and all use the same queue instead creating their own.
So you could create a named queue called "log" for all of the "log" workers. You would create a different named queue for say "foo" for all of the "foo" workers. Requests will be delivered round-robin to all consumers looking at the same queue.
To use RabbitMQ in round robin fashion, better to use direct exchange instead of topic exchange.
A direct exchange is ideal for the unicast routing of messages (although they can be used for multicast routing as well).
A queue binds to the exchange with a routing key K.
When a new message with routing key R arrives at the direct exchange, the exchange routes it to the queue if K = R.
Direct exchanges are often used to distribute tasks between multiple workers in a round robin manner. When doing so, it is important to understand that, messages are load balanced between consumers and not between queues.
I have a Topic exchange from which I'd like to distribute messages to two queues on two servers part of a cluster, in order to reduce memory pressure on any particular server. My consumers are periodically slow, and I sometimes run into the high memory watermark.
The way I tried to resolve this is by routing messages using an intermediate direct exchange, with two queues bound to the exchange:
a (topic) -> a1 (direct) -> q1/q2 (bound to routing key "a")
But the messages were routed to both queues, as AMQP intends. Anyone has ideas? What I need is an exchange that routes to one and only one queue, even if the routing key matches many queues. I'd prefer not to change my routing keys, but that could be arranged.
I found Selective routing with RabbitMQ, which may mean I'll need to implement my own routing logic. Hopefully, this already exists somewhere else.
You could perhaps use the Shovel plugin - http://www.rabbitmq.com/shovel.html - to move messages from your intermediate exchange to the two queues.
If you set up two shovels, both consuming from a single queue on the direct intermediate exchange, they should be able to fight over the messages coming in (I'm assuming that you don't care too much if the two recipient queues don't get the incoming messages in a strict round robin fashion). The shovels then each publish to one of the two end queues, and can send through the ACKs from the end consumer.