AWS SQS AWS.SimpleQueueService.MessageNotInflight

What is AWS SQS AWS.SimpleQueueService.MessageNotInflight

Understanding AWS SQS

Amazon Simple Queue Service (SQS) is a fully managed message queuing service that enables you to decouple and scale microservices, distributed systems, and serverless applications. SQS eliminates the complexity and overhead associated with managing and operating message-oriented middleware, and empowers developers to focus on differentiating work.

Identifying the Symptom

When working with AWS SQS, you might encounter the error code AWS.SimpleQueueService.MessageNotInflight. This error indicates that an operation was attempted on a message that is not currently in flight. In flight messages are those that have been received from the queue by a consumer but have not yet been deleted or have not yet reached the end of their visibility timeout.

Common Observations

Developers often see this error when trying to change the visibility timeout of a message that is not being processed. This can happen if the message has already been deleted or if the visibility timeout has expired and the message has returned to the queue.

Explaining the Issue

The AWS.SimpleQueueService.MessageNotInflight error occurs because the message is not currently being processed by any consumer. In AWS SQS, messages are considered 'in flight' when they have been received by a consumer and are being processed. If a message is not in this state, operations like changing its visibility timeout cannot be performed.

Technical Details

When a message is received from the queue, it becomes invisible to other consumers for the duration of the visibility timeout. If the message is not deleted or its visibility timeout is not extended, it will become visible again after the timeout expires, and it will no longer be considered 'in flight'.

Steps to Resolve the Issue

To resolve the AWS.SimpleQueueService.MessageNotInflight error, ensure that the message is currently being processed before attempting to change its visibility. Here are the steps you can follow:

Verify Message State

Check if the message is still in the queue. Use the AWS Management Console or AWS CLI to list messages in the queue. If the message is not in the queue, it may have been processed and deleted, or the visibility timeout may have expired.

Ensure Message is In Flight

Receive the message using the ReceiveMessage API call. This will make the message 'in flight'. Once the message is in flight, you can change its visibility timeout using the ChangeMessageVisibility API call.

Additional Resources

For more information on handling messages in AWS SQS, refer to the following resources:

AWS SQS Basic Architecture AWS SQS FAQs