Provisioned Concurrency in AWS Lambda

1. Introduction

Provisioned Concurrency is a feature in AWS Lambda that keeps a specified number of Lambda function instances warm and ready to respond immediately. This ensures consistent low latency for functions that experience unpredictable bursts of traffic.

2. Key Concepts

2.1 What is Provisioned Concurrency?

Provisioned Concurrency allows you to pre-initialize a defined number of Lambda instances so they are ready to handle requests instantly. This is particularly useful for applications that require predictable performance.

2.2 Cold Starts vs Warm Starts

- **Cold Start**: Occurs when a Lambda function is invoked for the first time or after a period of inactivity. It involves the initialization of the execution environment, leading to increased latency.
- **Warm Start**: Happens when an already initialized execution environment is reused, resulting in lower latency.

Note: Provisioned Concurrency eliminates cold starts, ensuring that your function is always warm and ready to execute.

3. Setup Process

To enable Provisioned Concurrency, follow these steps:

Create or select an existing Lambda function in the AWS Management Console.
Navigate to the Configuration tab.
Click on Concurrency in the left sidebar.
Select Edit next to Provisioned Concurrency.
Specify the desired number of provisioned concurrent executions.
Save your changes.
Invoke your function to ensure that it scales as expected.

3.1 Example CLI Command

You can also enable Provisioned Concurrency via the AWS CLI using the following command:


aws lambda put-provisioned-concurrency-config \
    --function-name MyFunction \
    --qualifier $LATEST \
    --provisioned-concurrent-executions 5

4. Best Practices

Monitor function performance using AWS CloudWatch to adjust provisioned concurrency as needed.
Use Provisioned Concurrency for functions with predictable traffic patterns.
Test different configurations to find the optimal number of provisioned concurrent executions.
Combine with AWS Auto Scaling to manage costs effectively.

5. FAQ

What is the cost of using Provisioned Concurrency?

The cost is based on the amount of provisioned concurrency you reserve and the duration your function is executed. Refer to the AWS pricing page for detailed information.

Can I adjust the provisioned concurrency settings at any time?

Yes, you can adjust the settings whenever required through the AWS Management Console or CLI.

Is Provisioned Concurrency available in all AWS regions?

Provisioned Concurrency is generally available in all AWS regions, but it is recommended to check the AWS regional services list for the latest updates.