RabbitMQ: Consumers not processing messages in queue
For some named RabbitMQ queues, we run a check that messages are being
consumed. This is currently only the case for the
email_unpublishing queues. The queue name
should indicate the app responsible for consuming the queue.
This is different to the check that there are consumers. This alert catches the case where a consumer is connected to the queue but failing to process messages in a timely fashion.
The check is performed by connecting to RabbitMQ’s admin API, so the information given is from Rabbit’s point of view. It looks at the number of messages still to be delivered.
If the check succeeds, it will return the number of unprocessed messages in the queue.
If the check fails due to a build up of messages, it will report how many messages there are, and what the threshold is.
Consequences of message build-up
If messages are building up, it may indicate that the service which
consumes them has hit a problem, or there is an unusually high amount
of activity. For example, email alerts about updated content will not
be sent if the
email_alert_sevice queue isn’t being processed.
Unless there is a wider RabbitMQ failure, messages will not be lost - they will be processed once the problem is resolved.
The same approach as RabbitMQ: No consumers listening to queue.