[Bug] VM option 'UseG1GC' must be enabled via -XX:+UnlockExperimentalVMOptions in JDK 1.8

[engineerping]

Before Creating the Bug Report

• I found a bug, not just asking a question, which should be created in GitHub Discussions.

• I have searched the GitHub Issues and GitHub Discussions of this repository and believe that this is not a duplicate.

• I have confirmed that this bug belongs to the current repository, not other repositories of RocketMQ.

Runtime platform environment

OS: ("macOS 14.3.1 (23D60)")

RocketMQ version

branch: (release-5.2.0) version: (5.2.0) Git commit: (0b612ff)

JDK Version

Compiler: ("Oracle JDK 1.8.0_391") OS: ("macOS 14.3.1 (23D60)")

Describe the Bug

while I am creating Rocket MQ on my local by following https://rocketmq.apache.org/docs/quickStart/01quickstart/;
I got failed without any useful information. after reaching, I changed my shell command, the following information was shown:

$ sh ./mqbroker -n localhost:9876 --enable-proxy
Error: VM option 'UseG1GC' is experimental and must be enabled via -XX:+UnlockExperimentalVMOptions.
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.

So I have updated some commands and raised a PR.

Steps to Reproduce

Just follow the official document
https://rocketmq.apache.org/docs/quickStart/01quickstart/

when JDK 8 is in use, this problem will be reproduced.

What Did You Expect to See?

$ sh ./mqbroker -n localhost:9876 --enable-proxy
Tue Apr 02 00:18:04 HKT 2024 rocketmq-proxy startup successfully

What Did You See Instead?

Error: VM option 'UseG1GC' is experimental and must be enabled via -XX:+UnlockExperimentalVMOptions.
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.

Additional Context

I have raised a PR to avoid this problem

[ltamber]

I can't reproduce it using openjdk version "1.8.0_382", Maybe you are using an older JDK distributions, can you follow the instructions in bin/runbroker.sh to check the JAVA_MAJOR_VERSION.

[engineerping]

Thank you for your response, fine, the details are shown below :

1. After I followed the instructions in bin/runbroker.sh to check the JAVA_MAJOR_VERSION, the result is "8".

2. My JDK version is: Oracle JDK 1.8.0_391, and this is the only version of JDK in my laptop.

3. My OS version is: macOS 14.3.1 (23D60)

4. the errors are shown in the Red box below, once the parameter -XX:+UnlockExperimentalVMOptions was added, the result turned to successful (shown in the Green box below)

[ltamber]

I have tried to reproduce it on M1 Macbook and still had no issues, it might be specific to certain JDK versions ?

[engineerping]

Thank you, I will try Oracle JDK 1.8.0_291 on my laptop

[engineerping]

Yeah, This issue occurs on specific JDK versions:

1. Running With Oracle JDK 1.8.0_291, there is no problem

2. Running with Oracle JDK 1.8.0_391, this issue was reproduced

3. And my PR https://github.com/apache/rocketmq/pull/7997/files runs well for both Oracle JDK 1.8.0_291 and
   Oracle JDK 1.8.0_391

[caigy]

G1GC is stable and not experimental since jdk 7u4 (https://www.oracle.com/java/technologies/javase/7u4-relnotes.html). IMO the JDK provider should fix it and explain the reason for inconsistency with release notes, maybe G1GC is indeed unstable in that version (but it's rare).