What does the message visibility timeout feature in SQS ensure?

The message visibility timeout feature in Amazon Simple Queue Service (SQS) is designed to ensure that messages remain invisible to other consumers while they are being processed by a consumer. When a consumer retrieves a message from the queue, SQS sets a visibility timeout period during which that message cannot be delivered to any other consumer. This mechanism allows the consumer to process the message without the risk of duplicate processing by others.

If the message is processed successfully within the visibility timeout, it can be deleted from the queue. If the visibility timeout expires before the processing is completed, the message becomes visible in the queue again, allowing other consumers to take it for processing. This feature helps in managing the reliability of message processing, ensuring that all messages are eventually processed while preventing multiple consumers from handling the same message simultaneously.