[rules-users] StatefulKnowledgeSession leaves threads running

[Greg Barton]

I have seen similar behavior, though at the time I didn't have the opportunity to investigate the cause. (Sorry about not reporting it at the time.) Unlike the code below it was while calling session.fireUntilHalt(). (In a seperate thread.)  After calling session.halt() from another thread the fireUntilHalt() would exit, but the VM would not exit due to a non-daemon thread persisting.

--- On Thu, 7/16/09, Rafael Ribeiro <rafaelri at gmail.com> wrote:

> From: Rafael Ribeiro <rafaelri at gmail.com>
> Subject: Re: [rules-users] StatefulKnowledgeSession leaves threads running
> To: "Rules Users List" <rules-users at lists.jboss.org>
> Date: Thursday, July 16, 2009, 12:10 PM
> Hi Edson!
> 
>  as I've already mentioned I've modified the
> sample so, if you get the StockTick sample and replace the
> Main class this will run fine.
>  The sample shuts down fine but as I saw it sets the
> JFrame uses frame.setDefaultCloseOperation(
> WindowConstants.EXIT_ON_CLOSE ); which in turn makes the
> trick.
> 
> 
>  Below the code of my modified main class:
> 
> package org.drools.examples.broker;
> 
> 
> import org.drools.KnowledgeBase;
> import org.drools.KnowledgeBaseConfiguration;
> import org.drools.KnowledgeBaseFactory;
> 
> import org.drools.builder.KnowledgeBuilder;
> import org.drools.builder.KnowledgeBuilderFactory;
> import org.drools.builder.ResourceType;
> import org.drools.conf.EventProcessingOption;
> import org.drools.examples.broker.model.Company;
> 
> import org.drools.examples.broker.model.CompanyRegistry;
> import org.drools.examples.broker.model.StockTick;
> import org.drools.io.ResourceFactory;
> import org.drools.runtime.StatefulKnowledgeSession;
> import org.drools.runtime.rule.WorkingMemoryEntryPoint;
> 
> 
> public class Main {
>     private static final String RULES_FILE =
> "/broker.drl";
>     static StatefulKnowledgeSession session;
>     static WorkingMemoryEntryPoint tickStream;
> 
>     /**
>      * @param args
> 
>      */
>     public static void main(String[] args) throws
> Exception {
>         // set up and show main window
>         
>         CompanyRegistry companies = new
> CompanyRegistry();
>         
>         KnowledgeBuilder builder =
> KnowledgeBuilderFactory.newKnowledgeBuilder();
> 
>         try {
>             builder.add(
> ResourceFactory.newInputStreamResource(
> Main.class.getResourceAsStream( RULES_FILE ) ),
>                         
> ResourceType.DRL);
>         } catch ( Exception e ) {
>             e.printStackTrace();
> 
>         }
>         if( builder.hasErrors() ) {
>            
> System.err.println(builder.getErrors());
>             System.exit( 0 );
>         }
> 
>         KnowledgeBaseConfiguration conf =
> KnowledgeBaseFactory.newKnowledgeBaseConfiguration();
> 
>         conf.setOption( EventProcessingOption.STREAM
> );
>         KnowledgeBase kbase =
> KnowledgeBaseFactory.newKnowledgeBase( conf );
>         kbase.addKnowledgePackages(
> builder.getKnowledgePackages() );
>         
> 
>         session =
> kbase.newStatefulKnowledgeSession();
> 
>         session.setGlobal( "services", new
> BrokerServices() {
>             public void log(String message) {
>                
> System.out.println(message);                
> 
>             }
>         });
> 
>         for( Company company :
> companies.getCompanies() ) {
>             session.insert( company );
>         }
>         session.fireAllRules();
>         
>         tickStream =
> session.getWorkingMemoryEntryPoint( "StockTick
> stream" );
> 
>  
>         for (int i=10;i>0;i--) {
>             tickStream.insert(new
> StockTick("RHT", i*10,
> System.currentTimeMillis()));
>             session.getAgenda().getAgendaGroup(
> "evaluation" ).setFocus();
> 
>             session.fireAllRules();
>         }
>         session.dispose();
>         session.halt();
>         System.out.println("Still
> running...");
>     }
>     
> }
> 
> 
> regards,
> Rafael Ribeiro
> 
> 
> 2009/7/16 Edson Tirelli <tirelli at post.com>
> 
> 
>    Hi Rafael,
> 
>    Are you setting the MultithreadEvaluation option or is
> this using default options? Do you have an example code that
> shows this behavior?
> 
>    Thanks,
>      Edson
> 
> 
> 
> 2009/7/16 Rafael Ribeiro <rafaelri at gmail.com>
> 
> 
> 
> 
> Hi all,
> 
> 
> 
>  I've downloaded Drools fusion sample and started to
> make some changes to
> 
> the code (first of all wipe out the UI so I can test it
> easier).
> 
>  I tried to get to a minimal set so I can run a console
> main class and see
> 
> what happens but I am facing a strange behaviour.
> 
>  As soon as I start pushing events into the
> WorkingMemoryEntryPoint
> 
> ("StockTick stream") a Thread - not daemonized
> since it blocks shutdown from
> 
> ending - is spawned and this prevents my JVM from shutting
> down (obviously
> 
> if I call System.exit(0) it will but I am avoiding this).
> 
>  I've tried both to halt and dispose the session that
> this entry point
> 
> belongs but with no success. Does anyone know how could I
> get rid of this
> 
> thread?
> 
> 
> 
> best regards,
> 
> --
> 
> 
> 
> 
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> 
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