Question

You have configured AWS S3 event notification to send a message to AWS Simple Queue Service whenever an object is deleted. You are performing a ReceiveMessage API operation on the AWS SQS queue to receive the S3 delete object message onto AWS EC2 instance. For any successful message operations, you are deleting them from the queue. For failed operations, you are not deleting the messages. You have developed a retry mechanism which reruns the application every 5 minutes for failed ReceiveMessage operations. However, you are not receiving the messages again during the rerun. What could have caused this?

A. AWS SQS deletes the message after it has been read through ReceiveMessage API

B. You are using Long Polling which does not guarantee message delivery.

C. Failed ReceiveMessage queue messages are automatically sent to Dead Letter Queues. You need to ReceiveMessage from Dead Letter Queue for failed retries.

D. Visibility Timeout on the SQS queue is set to 10 minutes.

Answer 1

D. Visibility Timeout on the SQS queue is set to 10 minutes.

When a consumer receives and processes a message from a queue, the message remains in the queue. Amazon SQS doesn’t automatically delete the message. Because Amazon SQS is a distributed system, there’s no guarantee that the consumer actually receives the message (for example, due to a connectivity issue, or due to an issue in the consumer application). Thus, the consumer must delete the message from the queue after receiving and processing it.