Optimizing Java for AWS Lambda

Posted on Feb 8, 2023

AWS Lambda is a serverless computing platform that lets you run your code without provisioning or managing servers. Java is one of the supported programming languages for AWS Lambda, which makes it a great choice for many applications. However, to get the best performance from your Java-based AWS Lambda functions, you’ll need to follow a few best practices. In this blog post, I’ll go over some of the most important optimisation techniques for Java on AWS Lambda.

Minimise code and dependencies

The first and most important optimisation tip is to keep the size of your code and dependencies as small as possible. This is because AWS Lambda functions are loaded into memory, so the larger your code and dependencies, the more memory your function will consume. This can cause slower cold start times and increased memory usage, which can impact the overall performance of your function.

To minimize the size of your code and dependencies, you can use the following techniques:

  • Use minimal libraries and dependencies
  • Remove unnecessary code
  • Use smaller frameworks or libraries
  • Package your code and dependencies together in a single .jar file

Use the latest version of Java

AWS Lambda currently supports Java 8, 11 and 16. Java 11 is the latest version and is recommended as it offers improved performance, security, and stability compared to earlier versions. You can find the list of supported runtimes here.

Optimise memory usage

Memory usage is a key factor in the performance of your AWS Lambda function. If your function runs out of memory, it can cause your function to crash. To optimize memory usage, you can use the following techniques:

  • Allocate the minimum amount of memory necessary for your function
  • Monitor and optimize the memory usage of your function
  • Use the right data structures and algorithms
  • Use lazy initialization

Optimise cold start times

Cold start times refer to the time it takes for an AWS Lambda function to start executing after being triggered. To optimize cold start times, you can use the following techniques:

  • Minimize the size of your code and dependencies
  • Warm up your functions by triggering them regularly
  • Avoid using slow-starting or resource-intensive initializations
  • Use Provisioned Concurrency to reduce cold start times for high-traffic functions

Monitor and debug your functions

Finally, to optimize the performance of your AWS Lambda functions, it’s important to monitor and debug them. You can use Amazon CloudWatch Logs, AWS X-Ray, and other tools to track the performance of your functions and identify areas for improvement.

In conclusion, optimizing Java for AWS Lambda requires paying attention to the size of your code and dependencies, using the latest version of Java, optimizing memory usage, optimizing cold start times, and monitoring and debugging your functions. By following these best practices, you can ensure that your AWS Lambda functions run smoothly and efficiently, providing the best possible user experience for your customers.