---
title: "AWS Lambda function is not configured for function-level concurrent execution Limit"
canonical: "https://kb.cynergy.app/space/MD/1207992330/AWS%20Lambda%20function%20is%20not%20configured%20for%20function-level%20concurrent%20execution%20Limit"
format: markdown
---
**Description**

Setting concurrency for Lambda functions pre-configures execution environments for simultaneous requests, reducing latency. However, unregulated concurrency can lead to sudden cost increases and potential misuse. Introducing concurrency limits helps control rapid usage spikes, optimizing resource allocation while adjusting limits based on application needs.

**Fix - Build time**

## Terraform

- **Resource:** aws_lambda_function
- **Argument:** reserved_concurrent_executions

```
resource "aws_lambda_function" "example" {
   ...
+  reserved_concurrent_executions = 100
}

```

## CloudFormation

- **Resources:** AWS::Lambda::Function, AWS::Serverless::Function
- **Argument:** Properties/ReservedConcurrentExecutions

```
Type: AWS::Lambda::Function
Properties: 
  ...
  ReservedConcurrentExecutions: 100
  ...

```