8:38 a.m.
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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