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Java UUID Generation: Performance Impact

Java developers tend to use the ‘java.util.UUID#randomUUID()’ API to generate a UUID (Universally Unique Identifier) number (i.e., ‘b8bbcbed-ca07-490c-8711-5118ee0af2f9’). Under certain circumstances, using this API can affect your application’s availability. Let’s discuss this API in this post with a real-world example.

How Does the ‘java.util.UUID#randomUUID()’ API Work?

java.util.UUID#randomUUID() API internally uses ‘entropy‘ in the operating system to generate a unique number. What does ‘entropy’ mean? The Linux kernel uses certain techniques like a user’s mouse movements, variance in the hardware fan noise, variance in the noise of the device drivers, etc. to generate random numbers. When there is a lack of ‘entropy’ in the operating system, then random number generation will slow down. When there is a slowdown, application threads that are calling this ‘java.util.UUID#randomUUID()’ API call will be put in a BLOCKED state, and they wouldn’t be able to progress further.

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Spring Boot Pet Clinic App: A Performance Study

Spring pet clinic application is a sample application developed by the Spring Framework developers to demonstrate the capabilities of Spring Boot, Spring MVC, and Spring Data Framework. We set out to conduct a performance test on this application and see whether we can identify any performance bottlenecks.

Environment Setup

We cloned the Spring pet clinic application’s official Github repository and followed instructions to build a JAR file. Once the JAR file was ready, we launched the application on http://localhost:8080.