What is CRAC?

CRAC typically refers to Coordinated Restore at Checkpoint. It is a mechanism used to reduce Java application startup time. It works by creating a checkpoint of the running application state (memory, CPU, etc.) and then restoring from that checkpoint at a later time. This avoids the need to re-initialize the application from scratch, significantly speeding up startup. It is used for quicker scaling of Java applications (especially useful in cloud environments like Kubernetes), faster recovery from failures, and improved developer experience by reducing deployment times. However, not all applications can be checkpointed and restored without modification and appropriate testing is recommended.