Recursive Lambda Function Invocation

Liam Greenamyre

Service Category

Compute

Cloud Provider

AWS

Service Name

AWS Lambda

Inefficiency Type

Recursive Invocation Misconfiguration

Explanation

Recursive invocation occurs when a Lambda function triggers itself directly or indirectly, often through an event source like SQS, SNS, or another Lambda. This loop can be unintentional — for example, when the function writes output to a queue it also consumes. Without controls, this can lead to runaway invocations, dramatically increasing cost with no business value.

Relevant Billing Model

* Billed per request and per millisecond of execution time * Recursive invocations amplify both request count and total execution duration

Detection

Review Lambda functions for high and sustained invocation rates with no matching business activity
Review event source and destination configurations for circular references (e.g., writing back to a triggering SQS queue)
Check CloudWatch Logs for repetitive invocation patterns with identical payloads
Correlate Lambda cost spikes with recent deployments or configuration changes
Assess if DLQs or concurrency limits are missing from functions with self-trigger patterns

Remediation

Refactor logic to prevent self-invocation or recursive event loops
Avoid writing to the same queue or stream that triggers the function
Implement Dead Letter Queues to prevent retry loops
Set concurrency limits using `ReservedConcurrency` or `MaximumRetryAttempts`
Utilize anomaly detection software to flag unusual invocation or cost patterns
Monitor function triggers and outputs as part of deployment validation

Relevant Documentation

https://docs.aws.amazon.com/lambda/latest/dg/invocation-eventsourcemapping.html
https://docs.aws.amazon.com/lambda/latest/dg/configuration-concurrency.html
https://docs.aws.amazon.com/lambda/latest/dg/invocation-async.html\#invocation-dlq
https://aws.amazon.com/lambda/pricing/

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