Race condition in MVELDialect ----------------------------- Key: JBRULES-2821 URL: https://jira.jboss.org/browse/JBRULES-2821 Project: Drools Issue Type: Bug Security Level: Public (Everyone can see) Components: drools-compiler Affects Versions: 5.1.1.FINAL Environment: JDK 1.6.0_20 Mac OS X 10.6.5 Reporter: Doug Pedrick Assignee: Mark Proctor Multiple threads loading different rulesets (each having local copies of KnowledgeBuilderConfiguration, KnowledgeBuilder, KnowledgeBaseConfiguration, and KnowledgeBase) can result in a race condition with the AbstractParser.OPERATIONS hash map in MVEL. MVELDialect and MVELExprAnalyzer both invoke ExpressionCompiler.compile. MVELDialect.compile calls AbstractParser.setLanguageLevel which clears and reloads the OPERATIONS static HashMap. It does so while holding COMPILER_LOCK. MVELExprAnalyzer calls ExpressionCompiler.compile without holding COMPILER_LOCK, resulting in OPERATIONS sometimes being empty when called, causing an NPE when attempting to autobox an Operator Integer to primitive. There are other areas in Drools code that ultimately depend on OPERATIONS and should be protected as well. java.lang.NullPointerException at org.mvel2.compiler.ExpressionCompiler._compile(ExpressionCompiler.java:250) at org.mvel2.compiler.ExpressionCompiler.compile(ExpressionCompiler.java:68) at org.drools.rule.builder.dialect.mvel.MVELExprAnalyzer.analyzeExpression(MVELExprAnalyzer.java:86) at org.drools.rule.builder.dialect.mvel.MVELDialect.analyzeExpression(MVELDialect.java:461) at org.drools.rule.builder.dialect.mvel.MVELDialect.analyzeExpression(MVELDialect.java:446) at org.drools.rule.builder.dialect.mvel.MVELPredicateBuilder.build(MVELPredicateBuilder.java:50) at org.drools.rule.builder.PatternBuilder.build(PatternBuilder.java:654) at org.drools.rule.builder.PatternBuilder.rewriteToEval(PatternBuilder.java:482) at org.drools.rule.builder.PatternBuilder.build(PatternBuilder.java:340) at org.drools.rule.builder.PatternBuilder.buildConstraint(PatternBuilder.java:264) at org.drools.rule.builder.PatternBuilder.build(PatternBuilder.java:213) at org.drools.rule.builder.PatternBuilder.build(PatternBuilder.java:108) at org.drools.rule.builder.GroupElementBuilder.build(GroupElementBuilder.java:69) at org.drools.rule.builder.GroupElementBuilder.build(GroupElementBuilder.java:43) at org.drools.rule.builder.GroupElementBuilder.build(GroupElementBuilder.java:69) at org.drools.rule.builder.RuleBuilder.build(RuleBuilder.java:79) at org.drools.compiler.PackageBuilder.addRule(PackageBuilder.java:1154) at org.drools.compiler.PackageBuilder.addPackage(PackageBuilder.java:636) at org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:266) at org.drools.compiler.PackageBuilder.addKnowledgeResource(PackageBuilder.java:458) at org.drools.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:28) -- This message is automatically generated by JIRA. - For more information on JIRA, see: http://www.atlassian.com/software/jira