Infinite retries due to exceeded SQS visibility timeout

Hello.

Basically, the application must be designed so that there is no problem even if the application processes SQS messages redundantly.
https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/standard-queues-at-least-once-delivery.html

If this occurs, the copy of the message isn't deleted on that unavailable server, and you might get that message copy again when you receive messages. Design your applications to be idempotent (they should not be affected adversely when processing the same message more than once).

The Lambda documentation recommends setting the visibility timeout to 6 times the execution time.
Therefore, I thought it would be a good idea to set the visibility timeout to a fairly long period even if you are using ECS.
https://docs.aws.amazon.com/lambda/latest/dg/with-sqs.html

To allow your function time to process each batch of records, set the source queue's visibility timeout to at least six times the timeout that you configure on your function. The extra time allows for Lambda to retry if your function is throttled while processing a previous batch.

If you set up a dead letter queue and adjust the maximum number of times messages can be received in the standard queue, it may be possible to process them without duplication to some extent.
https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-configure-dead-letter-queue.html

You should make sure that your visibility timeout is longer than the processing time. The challenge is that if the consumer fails to process the message and you configured a long visibility, it will take long time for the message to be processed. In this case the best practice would be to set a shorter visibility timeout and extend it from the consumer while it is processing the message.

In addition, set a DLQ and set the max retries to a small number, so that even if you do not extend the timeout, you will not get into a loop.