Java JVM Updates and Memory Improvements in Jenkins

In this post, we share our experience upgrading Jenkins from Java 17 to Java 21 and the impact this had on memory usage. After the move, we observed a reduction in out-of-the-field memory consumption from a monthly mean of 33–34 GB down to 28 GB. This improvement helped us reduce operational pressure and improve overall efficiency in our Jenkins environment. Why we upgraded to Java 21 Java 17 served us well as a stable long-term support release, but as part of our ongoing platform modernization, we evaluated Java 21 for Jenkins.