Test Java 15 on Raspberry Pi with Azul Zulu JDK. Compare startup times and performance of Spring and Quarkus applications with VisualVM profiling.

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A hands-on experiment running Azul Zulu OpenJDK 15 on a Raspberry Pi, comparing startup times and memory/CPU usage against OpenJDK 11 using Spring and Quarkus REST applications. Startup times show no meaningful difference between JDK 11 and 15. VisualVM profiling reveals Quarkus on Zulu 15 uses notably less heap memory (50 MB vs 90 MB), while Spring shows slightly higher heap usage. The conclusion is that upgrading to Java 15 is not urgent based on performance alone, but each release brings bug fixes, security patches, and new features like text blocks (JEP 378).

Azul Zulu OpenJDK 15 on Raspberry Pi