# Excessive Lambda retries (retry storms) | Cloud Efficiency Hub Canonical: https://www.pointfive.co/efficiency-hub/inefficiencies/excessive-lambda-retries-retry-storms Retry storms occur when a function fails and is automatically retried repeatedly by the service that invoked it: asynchronous invocations (e.g.,... By: Liam Greenamyre Updated: 2026-09-28 [Cloud Efficiency Hub](https://www.pointfive.co/efficiency-hub) # Excessive Lambda Retries (Retry Storms) The short version Retry storms occur when a function fails and is automatically retried repeatedly by the service that invoked it: asynchronous invocations (e.g., EventBridge, SNS, S3) are retried twice by default after function errors, SQS event source mappings return a failed message to the queue after each visibility timeout until the queue's redrive policy (maxReceiveCount) moves it to a dead-letter queue or the message expires, and stream event source mappings (Kinesis, DynamoDB Streams) retry the entire batch until the records expire unless a retry limit is set. [Liam Greenamyre](https://www.linkedin.com/in/liam-greenamyre-01606310/) Principal Product Manager (Technical - External Services) @ Amazon Web Services (AWS) AWS service [AWS Lambda](https://www.pointfive.co/efficiency-hub/cloud-services/aws-lambda) Category [Compute](https://www.pointfive.co/efficiency-hub/service-category/compute) Reference CER-0213 Type Inefficient Configuration ## Explanation Why the waste happens and who it affects. If the error is persistent and unhandled, retries can accumulate rapidly - often invisibly - creating a large volume of billable executions with no successful outcome. This is especially costly when functions run for extended durations or have high memory allocation. ## Billing model The pricing dimensions that drive this cost. - Each retry counts as a separate request - Billed per millisecond of execution time for each retry - Retries from failed invocations can exponentially increase cost if not controlled ## How to detect 5 checks to find it in your estate. - Check for high error-to-success ratios in CloudWatch Metrics - Investigate spikes in invocation count after initial failure events - Correlate retries with common payloads and error messages - Review configurations for MaximumRetryAttempts and DLQs - Assess the presence of throttling, downstream timeouts, or missing exception handling ## How to fix 6 ways to remove the waste. - Configure DLQs to isolate and inspect failed invocations - Implement exponential backoff or circuit breaker patterns in retry logic - Set appropriate retry limits for each source: MaximumRetryAttempts and MaximumRecordAgeInSeconds on stream event source mappings (Kinesis, DynamoDB Streams), MaximumRetryAttempts (0-2) and maximum event age on asynchronous invocation settings, and a redrive policy with maxReceiveCount and a dead-letter queue on SQS source queues - Improve exception handling and idempotency in function code - Utilize anomaly detection software to alert on abnormal retry patterns - Monitor CloudWatch for retry-specific metrics and alarms ## Documentation Vendor references for pricing and configuration. - [Understanding retry behavior in Lambda - AWS Lambda docs.aws.amazon.com](https://docs.aws.amazon.com/lambda/latest/dg/invocation-retries.html) - [Capturing records of Lambda asynchronous invocations - AWS Lambda docs.aws.amazon.com](https://docs.aws.amazon.com/lambda/latest/dg/invocation-async-retain-records.html) - [How Lambda processes records from stream and queue-based event sources - AWS Lambda docs.aws.amazon.com](https://docs.aws.amazon.com/lambda/latest/dg/invocation-eventsourcemapping.html) - [Handling errors for an SQS event source in Lambda - AWS Lambda docs.aws.amazon.com](https://docs.aws.amazon.com/lambda/latest/dg/services-sqs-errorhandling.html) - [AWS Lambda Pricing aws.amazon.com](https://aws.amazon.com/lambda/pricing/) ## Related inefficiencies [Browse the library](https://www.pointfive.co/efficiency-hub) - AWS Lambda CER-0204 ### [Inefficient SnapStart Configuration in Lambda](https://www.pointfive.co/efficiency-hub/inefficiencies/inefficient-snapstart-configuration-in-lambda) SnapStart reduces cold-start latency, but when configured inefficiently, it can increase costs. For Python and .NET functions, high-traffic workloads can trigger frequent snapshot restorations, multiplying costs. Slow initialization code... Compute - AWS Lambda CER-0230 ### [Excessive Lambda Duration from Synchronous Waiting](https://www.pointfive.co/efficiency-hub/inefficiencies/excessive-lambda-duration-from-synchronous-waiting) Some Lambda functions perform synchronous calls to other services, APIs, or internal microservices and wait for the response before proceeding. During this time, the Lambda is idle from a compute perspective but still fully billed. This... Compute - AWS Lambda CER-0218 ### [Suboptimal Architecture Selection in AWS Lambda](https://www.pointfive.co/efficiency-hub/inefficiencies/suboptimal-architecture-selection-in-aws-lambda) Lambda functions default to the x86\_64 architecture, which is more expensive than Arm64. For many workloads, especially those written in interpreted languages (e.g., Python, Node.js) or compiled to architecture-neutral bytecode (e.g.,... Compute --- Source: the public page above. Product screenshots and illustrative interfaces are examples, not live customer data.