Recursive AWS Lambda Horror Stories and How to Avoid Them

Infinite recursion in AWS Lambda functions can lead to unexpectedly high costs due to Lambda's ability to scale rapidly and invoke near-instantaneously. Common causes of such loops include architectural design flaws, such as when a Lambda function is triggered by a service and writes back to it, creating a feedback loop, or through retry mechanisms in the code or triggered by external services. While AWS offers partial solutions like built-in recursive loop detection for certain services, these are not comprehensive and do not cover all scenarios or service interactions. To mitigate these risks, developers are encouraged to follow best practices, such as thoroughly researching and planning their Lambda architecture, carefully testing for edge cases, setting conservative concurrency limits, and monitoring usage with tools like Amazon CloudWatch. Additionally, setting low timeouts can help limit the financial damage of inadvertent loops, and users should stay informed about AWS's policies on refunds for accidental overcharges.