Why do my RabbitMQ channels keep closing?

Question

I\'m debugging some Java code that uses Apache POI to pull data out of Microsoft Office documents. Occasionally, it encounter a large document and POI crashes when it runs o

Answer 1

For those who wonder why their consuming channels are closing, check if you try to Ack or Nack a delivery more than once.

In the rabbitmq log you would see messages like:

operation basic.ack caused a channel exception precondition_failed: unknown delivery tag ...

Answer 2

Apparently, there are many reasons for the AMQP connection and/or channels to close abruptly. In my case, there was too many unacknowledged messages on the queue because the consumer didn't specify the prefetch_count so the connection was getting terminated every ~1min. Limiting the number of unacknowledged messages by setting the consumer's prefetch count to a non-zero value fixed the problem.

channel.basicQos(100); 

Answer 3

I'd like to add this information for other users who will be searching for this topic

Another possible reason for Receiving a Channel Closed Exception is when Publishers and Consumers are accessing Channel/Queue with different queue declaration/settings

Publisher

channel.queueDeclare("task_queue", durable, false, false, null);

Worker

channel.queueDeclare("task_queue", false, false, false, null);

From RabbitMQ Site

RabbitMQ doesn't allow you to redefine an existing queue with different parameters and will return an error to any program that tries to do that

Answer 4

Another reason in my case was that by mistake I acknowledged a message twice. This lead to RabbitMQ errors in the log like this after the second acknowledgment.

=ERROR REPORT==== 11-Dec-2012::09:48:29 ===
connection <0.6792.0>, channel 1 - error:
{amqp_error,precondition_failed,"unknown delivery tag 1",'basic.ack'}

After I removed the duplicate acknowledgement then the errors went away and the channel did not close anymore and also the AlreadyClosedException were gone.

Answer 5

I also had this problem. The reason for my case was that, first I built the queue with durable = false and in the log file I had this error message when I switched durable to true:

"inequivalent arg 'durable' for queue 'logsQueue' in vhost '/': received 'true' but current is 'false'"

Then, I changed the name of the queue and it worked for me. I assumed that the RabbitMQ server keeps the record of the built queues somewhere and it cannot change the status from durable to non-durable and vice versa.

Again I made durable=false for the new queue and this time I got this error

"inequivalent arg 'durable' for queue 'logsQueue1' in vhost '/': received 'false' but current is 'true'"

My assumption was true. When I listed the queues in rabbitMQ server by:

rabbitmqctl list_queues 

I saw both queues in the server.

To summarize, 2 solutions are: 1. renaming the name of the queue which is not a good solution 2. resetting rabbitMQ by:

rabbitmqctl stop_app
rabbitmqctl reset
rabbitmqctl start_app

Answer 6

An AMQP channel is closed on a channel error. Two common things that can cause a channel error:

• Trying to publish a message to an exchange that doesn't exist
• Trying to publish a message with the immediate flag set that doesn't have a queue with an active consumer set

I would look into setting up a ShutdownListener on the channel you're trying to use to publish a message using the addShutdownListener() to catch the shutdown event and look at what caused it.