CRaC support for AWS SDK for Java

[smoell]

Describe the feature

Hi all,

Coordinated Restore at Checkpoint (CRaC) is an OpenJDK project that provides a fast start and immediate performance for Java applications. It allows for starting a Java application and JVM from an image in a warmed-up form. The image is created from a running Java process at an arbitrary point of time (“checkpoint”). The start from the image (“restore”) continues from the point when the checkpoint was made

(Referencing #3336 )

Since CRaC is becoming increasingly popular with AWS customers and is easy to use - especially in combination with Spring Boot - the AWS SDK for Java should also support CRaC.

Reference implementation using Amazon EKS and Azul Zulu can be found here: https://aws.amazon.com/blogs/containers/using-crac-to-reduce-java-startup-times-on-amazon-eks/

Use Case

Fast start and immediate performance for Java applications, libraries need to support CRaC or customers have to implement custom logic for connection handling.

Proposed Solution

No response

Other Information

No response

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

AWS Java SDK version used

All SDK versions

JDK version used

Doesn't matter

Operating System and version

Doesn't matter

[debora-ito]

Reached out to @smoell directly, we'll need some help to understand exactly how the support would look like on the SDK side.

[benminter-treatwell]

Hi, adding my support for this initiative!

We would love to add CRaC to our suite of JVMs running EKS for fast scaling, although it's possible to do this via the creation of custom CRaC handlers it would be great if it would work out of the box, to minimise adding custom brittle code that would need maintaining.

Azul has some great documentation on integrating/debugging with Crac: https://docs.azul.com/core/release/january-2025/crac/crac-debugging

Essentially anything with open sockets, file handles etc needs to implement the crac Resource interface and properly close those connections.

[bhoradc]

This feature is now available in the SDK starting with version 2.54.0.

For standalone CRaC usage, see the developer guide section - Use SdkWarmUp with standalone CRaC.

Resources:

• Developer guide: Warm up SDK clients in the AWS SDK for Java 2.x
• API reference: SdkWarmUp
• 2.54.0 release notes

If you have any questions or run into issues, please open a new issue and we'll be happy to help.

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