JMX Exporter Jar Incompatibility: Current Release Not Supports Java 8

[simonhgao]

I encountered the following error while using the JMX Exporter:

java.lang.UnsupportedClassVersionError: com/linkedin/kafka/cruisecontrol/metricsreporter/CruiseControlMetricsReporter has been compiled by a more recent version of the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes class file versions up to 52.0
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
	at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
	at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:348)
	at org.apache.kafka.common.utils.Utils.loadClass(Utils.java:416)
	at org.apache.kafka.common.utils.Utils.newInstance(Utils.java:405)
	at org.apache.kafka.common.config.AbstractConfig.getConfiguredInstance(AbstractConfig.java:390)
	at org.apache.kafka.common.config.AbstractConfig.getConfiguredInstances(AbstractConfig.java:474)
	at kafka.server.DynamicMetricsReporters.createReporters(DynamicBrokerConfig.scala:799)

This error indicates that the current JMX Exporter Jar only supports Java 11 (class file version 55.0) and is not compatible with older Java runtime versions (e.g., Java 8, class file version 52.0).

After upgrading to Java 11, the issue was resolved and everything started up normally.

I suggest updating the release documentation to clearly state this version limitation so that users can better configure their environments and avoid similar compatibility issues.

Thank you!

[fstab]

This must be a bug in our build pipeline. The JAR should be compatible with Java 8. Thanks for reporting!

[dhoard]

@simonhgao the class com/linkedin/kafka/cruisecontrol/metricsreporter/CruiseControlMetricsReporter is from the Cruise Control project (https://github.com/linkedin/cruise-control) which requires Java 11.

The JMX Exporter supports Java 8. It is tested on...

alibabadragonwell/dragonwell:8
amazoncorretto:8
antublue/openlogic-openjdk:8
azul/zulu-openjdk:8
azul/prime:8
bellsoft/liberica-openjdk-debian:8
bitnami/java:1.8
eclipse-temurin:8
eclipse-temurin:8-alpine
ghcr.io/graalvm/jdk:java8
ibmjava:8
ibm-semeru-runtimes:open-8-jdk-focal
konajdk/konajdk:8
mcr.microsoft.com/openjdk/jdk:8-mariner
openjdk:8
registry.access.redhat.com/ubi8/openjdk-8-runtime:latest

[simonhgao]

My Kafka was previously running in a Java 8 environment, but after adding the Java agent, it reports an error. What should I do? Should I disable this reporter?

[dhoard]

Are you seeing the same exception?
What version of Kafka?

The Cruise Control project (https://github.com/linkedin/cruise-control) requires Java 11

[simonhgao]

The version of kafka is kafka_2.13-2.8.2.