[rules-users] Multi thread error

[Ronald R. DiFrango]

Pierre,

There is no need to rebuild the entire rules base with each thread.  You can
build the rule base statically at startup.  Then within your thread's just
do:

// Note this is 4.0 syntax:
final StatefulSession session = ruleBase.newStatefulSession();

A single working memory is thread safe and the call in the ruleBase to
create it is as well.

Ron

On 7/10/07, Pierre Paysant-Le Roux <pierre.paysant_leroux at travelsoft.fr>
wrote:
>
> Hi,
> I have a problem using Drools in a multi thread program. I want that
> several threads use there own working memory. There is an error when two
> thread are building the same PackageBuilder at the same time. The
> exception is:  java.lang.LinkageError: duplicate class definition.
>
> Here is a simple program that generates the error.
>
> package com.sample;
>
> import java.io.IOException;
> import java.io.InputStreamReader;
>
> import org.drools.compiler.DroolsParserException;
> import org.drools.compiler.PackageBuilder;
> import org.drools.compiler.PackageBuilderConfiguration;
>
> public class TestThreads {
>
>     public static void main(String[] args) {
>         for(int i = 0; i<2 ; i++) {
>             DroolsThread tt = new DroolsThread();
>             tt.start();
>         }
>     }
>
>     public static class DroolsThread extends Thread {
>
>         public void run() {
>             PackageBuilderConfiguration pkgBuilderCfg =
>                 new PackageBuilderConfiguration();
>             PackageBuilder builder = new PackageBuilder(pkgBuilderCfg);
>             try {
>                 builder.addPackageFromDrl(new
> InputStreamReader(DroolsTest.class.getResourceAsStream( "/Sample.drl" )));
>             } catch (DroolsParserException e) {
>                 e.printStackTrace();
>             } catch (IOException e) {
>                 e.printStackTrace();
>             }
>         }
>     }
> }
>
>
> I don't understand what to do to avoid the exception : using
> "synchronized" somewhere ? Can someone help me please ?
> Thanks
> Pierre
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