Details
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Bug
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Resolution: Done
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Major
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None
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7.2.0.Final, 7.3.0.Final, 7.7.0.Final
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None
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NEW
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NEW
Description
When parallel compilation is enabled, common structures are modified concurrently by KnowledgeBuilderImpl.initPackage, resulting in the following stack trace in Java 9/10.
Exception in thread "main" java.util.ConcurrentModificationException: java.util.ConcurrentModificationException
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:488)
at java.base/java.util.concurrent.ForkJoinTask.getThrowableException(ForkJoinTask.java:600)
at java.base/java.util.concurrent.ForkJoinTask.reportException(ForkJoinTask.java:678)
at java.base/java.util.concurrent.ForkJoinTask.invoke(ForkJoinTask.java:737)
at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateParallel(ForEachOps.java:159)
at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateParallel(ForEachOps.java:173)
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:233)
at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:497)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.compileRulesLevel(KnowledgeBuilderImpl.java:1238)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.compileRules(KnowledgeBuilderImpl.java:1218)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.compileKnowledgePackages(KnowledgeBuilderImpl.java:1056)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.addPackage(KnowledgeBuilderImpl.java:1047)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.addPackageFromDrl(KnowledgeBuilderImpl.java:553)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.addKnowledgeResource(KnowledgeBuilderImpl.java:773)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:2360)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:2349)
at Main.attempt(Main.java:48)
at Main.main(Main.java:29)
Caused by: java.util.ConcurrentModificationException
at java.base/java.util.HashMap.computeIfAbsent(HashMap.java:1139)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.initPackage(KnowledgeBuilderImpl.java:1146)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.createPackageRegistry(KnowledgeBuilderImpl.java:1109)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.lambda$getOrCreatePackageRegistry$0(KnowledgeBuilderImpl.java:1105)
at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1751)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.getOrCreatePackageRegistry(KnowledgeBuilderImpl.java:1105)
at org.drools.compiler.builder.impl.TypeDeclarationCache.createTypeDeclarationForBean(TypeDeclarationCache.java:262)
at org.drools.compiler.builder.impl.TypeDeclarationCache.getAndRegisterTypeDeclaration(TypeDeclarationCache.java:90)
at org.drools.compiler.builder.impl.TypeDeclarationBuilder.getAndRegisterTypeDeclaration(TypeDeclarationBuilder.java:69)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.getAndRegisterTypeDeclaration(KnowledgeBuilderImpl.java:1860)
at org.drools.compiler.rule.builder.PatternBuilder.processClassObjectType(PatternBuilder.java:305)
at org.drools.compiler.rule.builder.PatternBuilder.build(PatternBuilder.java:181)
at org.drools.compiler.rule.builder.PatternBuilder.build(PatternBuilder.java:151)
at org.drools.compiler.rule.builder.PatternBuilder.build(PatternBuilder.java:133)
at org.drools.compiler.rule.builder.GroupElementBuilder.build(GroupElementBuilder.java:66)
at org.drools.compiler.rule.builder.RuleBuilder.build(RuleBuilder.java:105)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.addRule(KnowledgeBuilderImpl.java:1281)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.lambda$compileRulesLevel$3(KnowledgeBuilderImpl.java:1242)
at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183)
at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:177)
at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1492)
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
at java.base/java.util.stream.ForEachOps$ForEachTask.compute(ForEachOps.java:290)
at java.base/java.util.concurrent.CountedCompleter.exec(CountedCompleter.java:746)
at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1603)
at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:177)
Looking at the code, it looks like additional concurrency-unsafe modifications are performed, since it accesses the mentioned HashMap to get a shared LinkedList which it then modifies.
Note that the stack trace above is obtained on Java 9/10, as JDK9 added the extra check to HashMap.computeIfAbsent, but the code relies on race conditions in any JDK version.
Attached a sample Java class source that can trigger the stack trace reliably on my machine (using OpenJDK 10)—should hopefully be reproducible using JDK9/JDK10 as long as the common ForkJoinPool has more than 1 thread.
Also attached a "drl" file with the rules generated by the sample class (not needed when testing, as the contents are generated by the sample class).
Attachments
Issue Links
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- Closed
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