I'm using FuseESB with ActiveMQ v5.7.0.fuse-71-047 (aka v5.7)
I have one virtual topic "VirtualTopic.xxx" and one subscriber which (using Camel) it set ut as follows:
from(activemq:Consumer.A.VirtualTopic.xxx?brokerURL="something")
.doSomething()
Eveything seems to run fine, and I can see messages being enqueued and dequeued from the
queue "Consumer.A.VirtualTopic.xxx"
My question: Should messages dequeue from VirtualTopic.xxx ones they are sent to Consumer.A.VirtualTopic.xxx? Consumer A is the only subscriber. Using JConsole, I can see messages being enqueued but dequeue and dispatch count is 0. Is something wrong here?
Related
I've a service A which is publishing message to Queue(Q-A).
I've a dead letter queue(DLQ) bounded to DLX with DLRK.
Queue A is bounded to an exchange(E-A) with a routing key(RA).
I've also set x-letter-exchange(DLX) and x-dead-letter-routing-key(DLRK) on Q-A with ttl-per-message on this queue to 60 seconds
The DLQ is also set with x-letter-exchange(E-A) and x-dead-letter-routing-key(DLRK) with ttl-per-message on this queue to 60 seconds.
With above configuration I'm trying to route the message to DLQ from Q-A after ttl expires and vice versa.
On the consumer side which is another service, I throw AMQPRejectAndDontRequeueException with defaultRequeueRejected set to fals.
The above configuration works fine when the consumer is up and throws the
exception.
But I'm trying to limit my queue size to 1 and then publish 3 messages to the Q-A and also shutting down the consumer. I see all the three messages placed in both Q-A and DLQ and eventually all the messages are dropped.
But if I don't set the queue limit to 1 or start the consumer, everything works fine.
I've also set the x-overflow to reject-publish and when there is overflow, I get a nack at the publisher and then I've a scheduler which publish it again to Q-A.
Note: Both exchanges are Direct and I'm using routing keys to bind it to respective queue.
Kindly, let me know if I'm missing something here and let me know need to share my config
After digging through, I think i finally found the answer from the link Dead-lettering dead-lettered messages in RabbitMQ
answer by pinepain
It is possible to form a cycle of dead-letter queues. For instance, this can happen when a queue dead-letters messages to the default exchange without specifiying a dead-letter routing key. Messages in such cycles (i.e. messages that reach the same queue twice) will be dropped if the entire cycle is due to message expiry.
So I think to solve the problem I need to create another consumer to consume from dead letter queue and publish it back to original queue from the consumer and not directly ttl from the dead letter queue. Please correct me if my understanding is right.
I may have arrived at this too late, But I think I can help you with this.
Story:
You want a retry queue to send dead messages to and retrieve and re-queue them in the main queue after a certain amount of time.
Solution:
Declare your main queue and bind it to an exchange. We call them main_queue and main_exchange and add this feature to the main_queue: x-dead-letter-exchange: retry_exchange
Create your retry queue and bind it to another exchange. We call these retry_queue and retry_exchange and add these features to the retry queue: x-dead-letter-exchange: main_exchange and x-message-ttl: 10000
With this combination, dead messages from main_queue will be sent to retry_queue and after 10 seconds they will be sent again to the main_queue which will they last indefinitely until a consumer declares them dead.
Note: This method works only if you publish your messages to the exchange and not directly in the queue.
I am using java client of
https://www.rabbitmq.com/tutorials/tutorial-six-java.html
. My setup is RPC. My server is creating queue and client is also creating same queue and sending the message. After receiving message server is performing some operation and sending result back to client.
Now if server created the queue and connect with it while queue get's deleted for some reason. The server is not throwing any exception and when the client is creating the same queue and putting messages server is not getting those messages either as it's not connected.
How do server knows that the queue get deleted?
Thanks so much
It sounds like the following situation is happening:
Queue A is created.
Consumer 1 subscribes to Queue A
Queue A is deleted while Consumer 1 is still active
Queue A is re-created (call it A')
Now, you're wondering why Consumer 1 is not getting any messages? You would have to re-subscribe your consumer. I don't usually delete queues, because there is no need to do so under any reasonable scenario (instead, use the queue.expires property to handle auto-deletion of queues).
According to the AMQP 0-9-1 Specification,
When a queue is deleted any pending messages are sent to a dead-letter
queue if this is defined in the server configuration, and all
consumers on the queue are cancelled.
So, based on the description of the behavior, this is a bug with the consumer. It should throw an exception or otherwise exit the consuming loop in this case. In any case, you'll have to re-subscribe to A' before you'll get any more messages.
Does anyone know if the pop operation on a RabbitMQ queue is atomic?
I have several processes reading from the same queue (the queue is marked as durable, running on version 2.0.0) and I am seeing some quite odd behaviour.
If your multiple processes are consuming messages from the same queue then they should never consume the same message.
Here are the caveats, though:
If a message has been delivered by the broker to one of your consumers and it rejects the message (or terminates before getting a chance to acknowledge it) then the broker will put it back on the same queue and it would be delivered to one of your remaining active consumers.
If your consumers are pulling from distinct queues -- each with a matching binding -- then the broker will put copies of the message on each queue and each consumer will get a copy of the same message.
I have two subscribers listening to a publisher.All th queues are on the same machine.To make subscriber power off i deleted the input queue of one of the subsriber. I am getting one exception in the generic host command output and no meesages are there in the Outgoing Queues. Is this behaviour is coz all things are in the same machine ?
To bring down a subscriber, just kill the process - no need to delete the queue. The reason you don't see pending messages in the outgoing queue is exactly because the queue is local.
ActiveMQ: 5.10.2 inside ServiceMix's Karaf OSGi
KahaDB persistence.
Default broker settings.
Default settings in connections(tcp://x.x.x.x:61616)
16 queues predefined in activemq.xml.
Two client connections to ActiveMQ. One for producer sessions, one for consumer sessions.
Producers send messages to all queues.
16 consumer sessions consumes messages.
All going ok, but:
If I reduce number of consumers to 1 (or 2 or three, I don't know where is threshold) so that messages from 1 queue are consuming and messages from another queues are storing.
While some time passing, I see this picture:
That 1 consumer stop receiving message. He think that there are no more messages.
From activemqweb I can see that message count on that consuming queue is > 0
From activemqweb I cannot see any messages in Message Browser in that consuming queue.
I can see messages from other queues in Message Browser.
If I start some other consumer(or restart activemq) to consume messages from different queue I see:
I start to see messages in first queue Message Browser(those that were sent before but haven't been seen after "freeze").
First queue continue to consuming
Second queue begin to consuming.
The "freeze" can occur again in some time and start consuming another queue will help again.
If I start all consumers I see no "message freeze".
If just stop and start consumer on "frozen" queue, nothing happens. It need to be done on "unfrozen queue" to "unfroze" "frozen queue".
It also happens if there is no active producer, only consumer.
What can it be?
Thank you.
Oups. I've found what it was.
It's just available memory exceeded.
I didn't set -Xms and -Xmx, so it run with only 512mb of max heap.
And when messages size stored and not consumed is closed to the top, I get these behavior.