These queues are best when there is only one consumer. All char types and actions are represented on the FIFO queue. Acknowledgement of the message is necessary in order to take the message off the queue. If no acknowledgement is received, the message is placed back onto the queue.
Our queues adhere to the following:
Each queue is set to the SQS FIFO queue defaults: visibility timeout is 30 seconds, and maximum message retention period is 4 days.
Since these are FIFO queues, maximum inflight messages per queue is 20,000. If that limit is hit, you won’t receive any overlimit errors (unlike Standard queues).
There is no dead letter or redrive policy set up on these queues; which means you can receive messages as many times without deleting them.