Thank you!
From: Jason Porter <[email protected]> Date: Monday, 27 October 2025 at 15:09 To: [email protected] <[email protected]> Subject: Re: Does 10.1 work with Java 21? You don't often get email from [email protected]. Learn why this is important<https://aka.ms/LearnAboutSenderIdentification> Support on 21 is one of the things we're working on for 10.2.0. -- Jason Porter Software Engineer He/Him/His IBM From: Doug Whitfield <[email protected]> Date: Monday, October 27, 2025 at 13:37 To: [email protected] <[email protected]> Subject: [EXTERNAL] Does 10.1 work with Java 21? This Message Is From an External Sender This message came from outside your organization. Report Suspicious<https://us-phishalarm-ewt.proofpoint.com/EWT/v1/AdhS1Rd-!-_FVHVY-Xk87-ls5TmWg8VGmuqlnuI5mIYv4P5-Yk-hehmIjYHIp0A3v4-NmAh3Fk9F0mgvuheTbIjDtNcLAq36ZTCH2U0UZR0dFqkNdnKSf81KIC_SMrB4sMRiejgD31E8BqItx$> I recognise the docs say “17+” but I wonder if Java 21 is part of the test suite. Drools 10.1.0 rule compilation fails on Java 21 (OpenJDK) with an UnsupportedOperationException during parallel rule compilation when creating a KieSession from a KJAR. Environment Java: OpenJDK 21 Drools: 10.1.0 OS: Windows Maven: 3.x Steps to Reproduce 1. Build a KJAR with Drools 10.1.0 2. Load via KieServices.Factory.get().getKieClasspathContainer() and create a KieSession from a KJAR 3. Trigger parallel rule compilation Error Details java.lang.RuntimeException: Rules compilation failed or interrupted at org.drools.compiler.builder.impl.processors.ImmutableRuleCompilationPhase.compileRulesLevel(ImmutableRuleCompilationPhase.java:285) ... (parallel execution stack trace using atomic primitives) Root cause: java.lang.UnsupportedOperationException: null at org.drools.compiler.rule.builder.ConstraintBuilder$DummyConstraintBuilder.setExprInputs(ConstraintBuilder.java:210) Stack Trace Highlights The failure occurs in parallel execution via ForkJoinPool: at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateParallel at org.drools.compiler.builder.impl.processors.ImmutableRuleCompilationPhase.lambda$compileRulesLevel$4 Indicates a failure during parallel compilation using Java 21's stream framework. Workarounds Attempted (None Successful) 1. System.setProperty("drools.parallelExecutionAllowed", "false") – not honored in 10.x 2. System.setProperty("drools.multithreadEvaluation", "false") – no effect 3. Downgrade to Drools 8.44 – DRL incompatibility with 10.x-compiled rules 4. -Djdk.reflect.useDirectMethodHandle=false – still fails with native reflection Expected Behavior Rules compile and execute successfully on Java 21 without errors. [Perforce Software] Douglas Whitfield | Enterprise Architect, OpenLogic Perforce Software<https://www.perforce.com> P +1 612.517.2100 Visit Us On: LinkedIn<https://www.linkedin.com/company/perforce> | YouTube<https://www.youtube.com/user/perforcesoftware> This e-mail may contain information that is privileged or confidential. If you are not the intended recipient, please delete the e-mail and any attachments and notify us immediately. CAUTION: This email originated from outside of the organization. Do not click on links or open attachments unless you recognize the sender and know the content is safe. This e-mail may contain information that is privileged or confidential. If you are not the intended recipient, please delete the e-mail and any attachments and notify us immediately.
