I am using RabbitMQ messaging service to send messages. I want to dequeue the messages that are sent on a scheduled basis and stop dequeuing the messages after 2 minutes, so that I can dequeue them on the next scheduled time.
Thanks,
R. Venkatesan
Looks like Time-To-Live Extensions is what you want. Setting per-queue ttl for 2 minutes will dead-letter messages that was published more than 2 minutes ago.
Related
I am facing a scenario where every message in the queue should be consumed after a delay that is achievable using TTL and Dead Letter Exchange in RabbitMQ but when a max TTL will be at the head than no other messages will be consumed.
I want to achieve that every message in the queue gets consumed after it's delay irrespective of its position in the queue.
Instead of relying on TTL and the dead-letter exchange you can use the delayed-message-exchange. With the delayed-message-exchange, the message is published to the queue only when its TTL expires. Consuming every message in the queue will require to add more consumers to the queue.
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 have a queue producer(NON_PERSISTENT) and a queue consumer connected to my ActiveMQ server. If a producer sends a message to a queue while the consumer is not connected to ActiveMQ, it seems it is stored and delivered when the consumer is up and connected to ActiveMQ.
I want ActiveMQ to ignore the message if the consumer is not connected at the time of delivery. How can I achieve this?
Thanks in advance.
Use a topic instead of a queue - this is the default behaviour for topics (unless a durable subscriber is used).
Otherwise, for queues, you can set a message expiry when sending the message. It will be discarded if not read within that time frame. Make sure to set enough time frame so that clock sync issues between servers won't be a factor. Let's say 2 minutes or so.
I have 2 RabbitMQ queues:
incoming_message => where I push all messages that I want to process later
incoming_message_dlx => where I push the message whose the processing failed
As you can supposed with its name, the incoming_message_dlx queue use the Dead Letter Exchange feature, that means when the message expires, it will be requeue to my incoming_message.
What I try to achieve is to increase the expiration of messages each time the processing failed and that they are push to the DLX queue.
The problem is that even if a message expired, it will not be requeue to my incoming_message while it's not at the bottom (head) of the queue. So if there is a message with an expiration time of 7 days in the DLX queue and that we enqueue a new message with the expiration time of 5 seconds, this message will only be requeue to the incoming_message after 7 days + 5 seconds...
I've found on the documentation that I can use my DLX queue as a priority queue and put a priority on my messages according to the expiration time, but it doesn't work as expected, the priority seems to be ignored.
However, when I use the RabbitMQ admin (management plugin) and that I get the first message of the queue, it's always the one with the higher priority, but the "internal consumer" of the DLX queue seems to ignore this priority.
Do you know what could be the problem?
Thanks a lot in advance.
PS: I'm using RabbitMQ server version 3.6.10.
as a queue structure(fifo),rabbitmq do expire from the head of the queue.
queue ttl contains 3 type:
Per-Queue Message TTL： x-message-ttl
Per-Message TTL： expiration
Queue TTL：x-expires
when you want the message just deliver on the ttl value ,try use multi level ttl queue.
you can predefined some dlx queue as you need.
eg: you want error message do retry in (5s,15s,60s), you can define 3 dlx queue by set different x-message-ttl value, and this 3 incoming_message_dlx queue binding the dlx router to the incoming_message;
but if you have a message ttl=30s ,you just prefdefind 3 queue with ttl(5s,15s,60s) , so where to diliver ? try priority queue.
offical doc
Messages which should expire will still only expire from the head of the queue. This means that unlike with normal queues,
even per-queue TTL can lead to expired lower-priority messages getting stuck behind
non-expired higher priority ones.
These messages will never be delivered, but they will appear in queue statistics.
expired lower-priority messages getting stuck behind non-expired higher priority ones
queue like [60s(p=1),30s(p=0)] will not happen!
we defined 3 queue ttl(5s,15s,60s),in order to prevent lower ttl message getting stucked , we push the message to the queue with flor ttl not ceil ttl；
so ttl=30s will deliver to queue which ttl=60s,and set priority=1
ttl=30s is between the predefined queue (15s,60s);
set ttl=60s queue's max-priority=1, default is 0;
deliver ttl=30s message with priority=1;
so the message in a queue just like [30,60,60,60,60].
ttl=30s will not be blocked by the ttl=60s.
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.