We have 3 JBoss EAP 7 servers which are configured to consume messages from ActiveMQ queues. The IN queue is for the request message and OUT queue is for the response message. There are multiple IN queues and corresponding OUT queues.
Assume a scenario where we want to take 1st application server down for maintenance. There can be N number of messages it has consumed from IN queue and in the process of doing the business logic.
How do we instruct the 1st application server not to pick any new messages, complete whatever it already picked from IN, and respond to OUT so that it can be taken for maintenance?
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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 have a RabbitMQ message queue and I want to publish multiple messages to the queue from a web service call ServiceA. Meantime, there is an another web service called ServiceB which is implemented for consuming the messages from the RabbitMQ same queue in an interval of 10 seconds time period. Is this use case possible with the implementation of the RabbitMQ queues?
Does RabbitMQ support to access the same queue by the publisher and consumer at the same time (simultaneously)?
ServiceB which is implemented for consuming the messages from the RabbitMQ same queue in an interval of 10 seconds time period.
It's a little bit strange to implement this by RabbitMQ. In RabbitMQ, consumer channel will receive message immediately unless its unAck messages reach the prefetch limit. I recommend to add a Buffer Cache (flush every 10 seconds) between RabbitMQ consumer and ServiceB.
Does RabbitMQ support to access the same queue by the publisher and consumer at the same time (simultaneously)?
In RabbitMQ, publisher can't access queue directly, you can only publish message to exchange, RabbitMQ Daemon will route message by the exchange binding rule. In other words, publisher and consumer can work independently and simultaneously.
I'm using RabbitMQ and need a message to be queued and consumed by multiple servers, but only one of the servers could confirm this message and only it would remove this message from the queue, even if other servers have consumed the message, but do not have removed it from the queue. I wonder how RabbitMQ can do this scenario ?
Is there a way to deliver messages that have been deadlettered because they were rejected to a different queue than messages that have expired?
I can imagine building a service that reads the 'all dead' queue, parses the header xdeath reason and separates the messages by reason, posting them on different queues.
But is there also a way in RabbitMQ to do a similar thing?
(The use case: I want to process the expired messages by a superfast service to quickly reduce the backlog (for instance after we have a database failure). But the rejected messages need to be handled by a service with a lot of debug logging enabled.)
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.