[rules-users] Drools KnowledgeBuilderImpl.add(...) not thread safe???
Wolfgang Laun
wolfgang.laun at gmail.com
Wed Dec 16 04:52:07 EST 2009
Leaving the issue of thread safety aside, I wonder why it should be
necessary to
build the same KnowledgeBase 200 times? I'd say you are wasting a lot of
cycles.
It ought to be possible to derive many independent (and concurrent) sessions
from one kbase.
-W
2009/12/15 Grigoriev, Grigoriy <Grigoriy.Grigoriev at t-systems.ru>
> I have already mentioned this issue previously here (see
> http://n3.nabble.com/Mvel-and-multithreading-td50133.html)
>
>
>
> Maybe I have described the problem not detailed enough.
>
>
>
> We are using Drools version 5.0.1 and have a concrete problem with it in
> our production environment. Our customer looks already interrogative at the
> developer team and have „questions“ about drools… please help! J
>
>
>
> 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.
>
>
>
> I have run this project on two PCs:
>
> 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.
>
>
>
> Could you please help us to clear this problem? Are we doing here something
> wrong?
>
> If it should be an drools error, could you please create an issue for it?
>
>
>
> Thanks!
>
>
>
> Wbr,
>
> Grigoriy Grigoriev
>
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
>
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