I'm working with RabbitMQ and Spring amqp where I would prefer not to lose messages. By using exponential back off policy for retrying, I'm potentially blocking my consumers which they could be working off on messages they could handle. I'd like to give failed messages several days to retry with the exponential back off policy, but I don't want a consumer blocking for several days and I want it to keep working on the other messages.
I know we can achieve this kind of functionality with ActiveMQ(Retrying messages at some point in the future (ActiveMQ)), but could not find a similar solution for RabbitMQ.
Is there a way to achive this with Spring amqp and RabbitMQ?
You can do it via the dead letter exchange. Reject the message and route it to the DLE/DLQ and have a separate listener container that consumes from the DLQ and stop/start that container as needed.
Or, instead of the second container you can poll the DLQ using the RabbitTemplate receive (or receiveAndConvert) methods (on a schedule) and route the failed message(s) back to the primary queue.
Related
I'm doing a test to see how the flow control behaves. I created a fast producer and slow consumers and set my destination queue policy highwater mark to 60 percent..
the queue did reach 60% so messages now went to the store, now the store is full and blocking as expected..
But now i cannot get my consumer to connect and pull from the queue.. Seem that blocking is also blocking the consumer from getting in to start pulling from the queue..
Is this the correct behavior?
The consumer should not be blocked by flow-control. Otherwise messages could not be consumed to free up space on the broker for producers to send additional messages.
So this issues surfaced when I was using a on demand jms service. The service will queue or dequeue via a REST services. The consumers are created on demand.. If the broker is being blocked as im my case being out of resource, then you cannot create a new consumer.
I've since modified the jms service to use a consumer pool(implemented a object pool pattern). The consumer pool is initialized when the application starts and this resolved the blocking issue
I want to obtain number of unacknowledged messages in RabbitMQ queue.
How can I achieve it?
I tried to use HTTP API, concretely /api/queues/vhost/name, but it always returns 0 messages_unacknowledged and messages
The HTTP (REST) API (management plugin) is not real time; it lags reality.
rabbitAdmin.getQueueProperties(queueName).get(org.springframework.amqp.rabbit.core.RabbitAdmin.QUEUE_MESSAGE_COUNT) does the job
RabbitAdmin is a bean which is automatically configured by Spring Boot.
I am using Spring AMQP to publish messages to RabbitMQ. Consider a scenario:
1. Java client sends a message to MQ usin amqpTemplate.convertAndSend()
2. But RabbitMQ is down OR there's some n/w issue
In this case the message will be lost? OR
Is there any way it'll be persisted and will be retried?
I checked the publish-confirm model as well but as I understood, ultimately we've to handle the nack messages through coding on our own.
The RabbitTemplate supports adding a RetryTemplate which can be configured whit whatever retry semantics you want. It will handle situations when the broker is down.
See Adding Retry Capabilities.
You can use a transaction or publisher confirms to ensure rabbit secured the message.
I have a requirement to load messages from two queues and i am using ActiveMQ I have to implement the Retry mechanism in case of any error or network or application server failure and load back into the same Queue. Also, I want to load any poison messages to DLQ.
Please let me know if I can acheive these through Spring JMS. Also, please advise some good examples to accomplish this task. I checked Spring JMS documentation and have not much details in that.
This is a broker function with ActiveMQ - just configure the broker with the appropriate policies.
If using a DefaultMessageListenerContainer, you must use transacted sessions; then, if the listener throws an exception the message will be rolled back onto the queue and the broker's retry/DLQ policies kick in.
See the Spring documentation about enabling transactions.
I use ActiveMQ as a job dispatcher. Which means one master sends job messages to ActiveMQ, and multiple slaves grab job messages from ActiveMQ and process them. When slaves finish one job, they send a message with job_id back to ActiveMQ.
However, slaves are unreliable. If one slave doesn't respond before a period of time, we can assume the slave is down, and try redeliver the sent job message.
Are there any good ideas to realize this re-delivery?
Typically a consumer handles redelivery so that it can maintain message order while a message appears as inflight on the broker. This means that redelivery is limited to a single consumer unless that consumer terminates. In this way the broker is unaware of redelivery.
In ActiveMQ v5.7+ you have the option of using broker side redelivery, it is possible to have the broker redeliver a message after a delay using a resend. This is implemented by a broker plugin that handles dead letter processing by redelivery via the scheduler. This is useful when total message order is not important and where through put and load distribution among consumers is. With broker redelivery, messages that fail delivery to a given consumer can get immediately re-dispatched.
See the ActiveMQ documentation for an example of setting this up in the configuration file.