redhat-developer / redhat-developer/vscode-java
Java package taking 100% CPU under very specific conditions
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Since Jan 30, 2026.
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- TypeScript
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Description
Here are the minimal conditions needed to reproduce this issue:
- A Java package has a dependency on Lombok.
- A method uses Lombok's
@NonNullon a parameter. - The first line of the method is a comment.
- The line after the comment is NOT empty.
- The
lombok.nonNull.exceptionType = JDKoption is set in alombok.configfile.
If you open this project in VS Code with the redhat.java extension, any modification in that same file that does not break the above criteria (such as adding a comment on the last line and saving) will take 100% of one CPU core. Do it 5 times, and it will take 5 cores!
This high CPU usage stops after a while, but it makes the whole machine unresponsive if you make several modifications quickly.
You can use this minimal repo to reproduce the bug: ipkiss42/vscode-java-4052.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Assessment
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