[jboss-jira] [JBoss JIRA] Created: (JBRULES-2380) KnowledgeBuilderImpl.add(...) throws org.mvel2.CompileException when executed concurrently for the same resource

Grigoriy Grigoriev (JIRA) jira-events at lists.jboss.org
Wed Dec 16 09:38:31 EST 2009


KnowledgeBuilderImpl.add(...) throws org.mvel2.CompileException when executed concurrently for the same resource
----------------------------------------------------------------------------------------------------------------

                 Key: JBRULES-2380
                 URL: https://jira.jboss.org/jira/browse/JBRULES-2380
             Project: Drools
          Issue Type: Quality Risk
      Security Level: Public (Everyone can see)
         Environment: Drools 5.0.1
core 2 duo @ 2.6 ghz, win xp prof sp3, sun jdk 1.6.0_17
Pentium Dual CPU E2160 @ 1.8GHz, XP prof SP3, sun jdk 1.6.0_16.
            Reporter: Grigoriy Grigoriev
            Assignee: Mark Proctor


Let us assume a multithreaded application, that tries to initialise & start several processes using a StatefulKnowledgeSession in order to use in these processes rule flow. The flow in all the processes is the same but every process instance must have an own StatefulKnowledgeSession instance because of stateful session.

Actually the problem:

At the initializing phase occurs an org.mvel2.CompileException exception from time to time at KnowledgeBuilder.add(...):
Exception in thread "Thread-60" [Error: incomplete statement:  (possible use of reserved keyword as identifier: )]
[Near : {... globals != empt ....}]
                      ^
[Line: 0, Column: 0]
      at org.mvel2.MVELInterpretedRuntime.parseAndExecuteInterpreted(MVELInterpretedRuntime.java:153)
      at org.mvel2.MVELInterpretedRuntime.parse(MVELInterpretedRuntime.java:44)
      at org.mvel2.MVEL.eval(MVEL.java:514)
      at org.mvel2.templates.res.IfNode.eval(IfNode.java:61)
      at org.mvel2.templates.res.TextNode.eval(TextNode.java:46)
      at org.mvel2.templates.res.TerminalNode.eval(TerminalNode.java:39)
      at org.mvel2.templates.res.ForEachNode.eval(ForEachNode.java:116)
      at org.mvel2.templates.res.TextNode.eval(TextNode.java:46)
      at org.mvel2.templates.res.TerminalNode.eval(TerminalNode.java:39)
      at org.mvel2.templates.res.IfNode.eval(IfNode.java:64)
      at org.mvel2.templates.res.TextNode.eval(TextNode.java:46)
      at org.mvel2.templates.res.ExpressionNode.eval(ExpressionNode.java:53)
      at org.mvel2.templates.res.TextNode.eval(TextNode.java:46)
      at org.mvel2.templates.TemplateRuntime.execute(TemplateRuntime.java:195)
      at org.mvel2.templates.TemplateRuntime.execute(TemplateRuntime.java:190)
      at org.mvel2.templates.TemplateRuntime.execute(TemplateRuntime.java:180)
      at org.mvel2.templates.TemplateRuntime.execute(TemplateRuntime.java:169)
      at org.drools.rule.builder.dialect.java.AbstractJavaRuleBuilder.generatTemplates(AbstractJavaRuleBuilder.java:126)
      at org.drools.rule.builder.dialect.java.JavaConsequenceBuilder.build(JavaConsequenceBuilder.java:128)
      at org.drools.rule.builder.RuleBuilder.build(RuleBuilder.java:86)
      at org.drools.compiler.PackageBuilder.addRule(PackageBuilder.java:1159)
      at org.drools.compiler.PackageBuilder.addPackage(PackageBuilder.java:649)
      at org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:290)
      at org.drools.compiler.PackageBuilder.addKnowledgeResource(PackageBuilder.java:488)
      at org.drools.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:25)
      at com.myfirm.RuleFlowProcess.init(RuleFlowProcess.java:25)
      at com.myfirm.RuleFlowProcess.clone(RuleFlowProcess.java:53)
      at com.myfirm.ThreadTest$CloneThread.run(ThreadTest.java:35)
Caused by: java.lang.NullPointerException
      at org.mvel2.MVELInterpretedRuntime.parseAndExecuteInterpreted(MVELInterpretedRuntime.java:113)
      ... 27 more
Exception in thread "Thread-72" [Error: incomplete statement:  (possible use of reserved keyword as identifier: )]
[Near : {... declarations != empt ....}]
                           ^
[Line: 0, Column: 0]
      at org.mvel2.MVELInterpretedRuntime.parseAndExecuteInterpreted(MVELInterpretedRuntime.java:153)
      at org.mvel2.MVELInterpretedRuntime.parse(MVELInterpretedRuntime.java:44)
      at org.mvel2.MVEL.eval(MVEL.java:514)
      at org.mvel2.templates.res.IfNode.eval(IfNode.java:61)
      at org.mvel2.templates.res.TextNode.eval(TextNode.java:46)
      at org.mvel2.templates.res.ExpressionNode.eval(ExpressionNode.java:53)
      at org.mvel2.templates.res.TextNode.eval(TextNode.java:46)
      at org.mvel2.templates.res.ExpressionNode.eval(ExpressionNode.java:53)
      at org.mvel2.templates.res.TextNode.eval(TextNode.java:46)
      at org.mvel2.templates.res.TerminalNode.eval(TerminalNode.java:39)
      at org.mvel2.templates.res.ForEachNode.eval(ForEachNode.java:116)
      at org.mvel2.templates.res.TextNode.eval(TextNode.java:46)
      at org.mvel2.templates.res.TerminalNode.eval(TerminalNode.java:39)
      at org.mvel2.templates.res.ForEachNode.eval(ForEachNode.java:116)
      at org.mvel2.templates.res.TextNode.eval(TextNode.java:46)
      at org.mvel2.templates.res.ExpressionNode.eval(ExpressionNode.java:53)
      at org.mvel2.templates.res.TextNode.eval(TextNode.java:46)
      at org.mvel2.templates.res.ExpressionNode.eval(ExpressionNode.java:53)
      at org.mvel2.templates.res.TextNode.eval(TextNode.java:46)
      at org.mvel2.templates.TemplateRuntime.execute(TemplateRuntime.java:195)
      at org.mvel2.templates.TemplateRuntime.execute(TemplateRuntime.java:190)
      at org.mvel2.templates.TemplateRuntime.execute(TemplateRuntime.java:180)
      at org.mvel2.templates.TemplateRuntime.execute(TemplateRuntime.java:169)
      at org.drools.rule.builder.dialect.java.AbstractJavaRuleBuilder.generatTemplates(AbstractJavaRuleBuilder.java:135)
      at org.drools.rule.builder.dialect.java.JavaConsequenceBuilder.build(JavaConsequenceBuilder.java:128)
      at org.drools.rule.builder.RuleBuilder.build(RuleBuilder.java:86)
      at org.drools.compiler.PackageBuilder.addRule(PackageBuilder.java:1159)
      at org.drools.compiler.PackageBuilder.addPackage(PackageBuilder.java:649)
      at org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:290)
      at org.drools.compiler.PackageBuilder.addKnowledgeResource(PackageBuilder.java:488)
      at org.drools.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:25)
      at com.myfirm.RuleFlowProcess.init(RuleFlowProcess.java:25)
      at com.myfirm.RuleFlowProcess.clone(RuleFlowProcess.java:53)
      at com.myfirm.ThreadTest$CloneThread.run(ThreadTest.java:35)
Caused by: java.lang.NullPointerException
      at org.mvel2.MVELInterpretedRuntime.parseAndExecuteInterpreted(MVELInterpretedRuntime.java:113)
      ... 33 more

To demonstrate this problem I have created a simple test maven project that reproduces this error (s. attach):
I have a class that creates & inits stateful knowledge session in a init method (RuleFlowProcess):

/** 

 * inits the rule flow 

 */

public class RuleFlowProcess {
      private StatefulKnowledgeSession ksession;

      public void init() {
            KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
            kbuilder.add(ResourceFactory.newClassPathResource("threadSafeTest.rf"), ResourceType.DRF);
            kbuilder.add(ResourceFactory.newClassPathResource("testRules1.drl"), ResourceType.DRL);
            kbuilder.add(ResourceFactory.newClassPathResource("testRules2.drl"), ResourceType.DRL);
            kbuilder.add(ResourceFactory.newClassPathResource("testRules3.drl"), ResourceType.DRL);
            kbuilder.add(ResourceFactory.newClassPathResource("testRules4.drl"), ResourceType.DRL);          

            KnowledgeBuilderErrors errors = kbuilder.getErrors();
            if (errors.size() > 0) {
                  StringBuilder errorString = new StringBuilder();
                  for (KnowledgeBuilderError error : errors) {
                        errorString.append(error);
                  }
                  throw new RuntimeException(errorString.toString());
            }
            KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();
            kbase.addKnowledgePackages(kbuilder.getKnowledgePackages());
            ksession = kbase.newStatefulKnowledgeSession();
      }
...
}
I create & init concurrently in several (200) threads this RuleFlowProcess and some threads crash with this exceptions while adding the resources.

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