[rules-dev] Can't execute rules twice with a second classloader

[Aaron Dixon]

This is exactly right. My only question is why the internal Drools
cache isn't scoped to the RuleBase or the session -- why is it scoped
to the VM...is it a static cache? If time permits I can try to look
into this, not sure how soon I could get to it , though. Is there an
issue in your bug tracking system for this?

On 7/14/07, Mark Proctor <mproctor at codehaus.org> wrote:
>
>  I think this is related to  this:
>          FooClassLoader loader1 = new FooClassLoader(original);
>          Class instance1 = loader1.loadClass( "test.drools.classloader.Foo"
> );
>          FooClassLoader loader2 = new FooClassLoader(original);
>          Class instance2 = loader2.loadClass( "test.drools.classloader.Foo"
> );
>          System.out.println( instance1.isAssignableFrom( instance2 ) );
>
>  Notice the instances are not assignable. We generate bytecode field
> readers, and cache them by string name. Now I imagine the second instance is
> using that same cache with the code generated off the first classloader, and
> thus providing the error. I'm not sure how to fix this.... expect it's a
> point release fix now - patch welcome :)
>
>  Mark
>
>  Aaron Dixon wrote:
> Here you go. It's an eclipse project. Only dependencies are the Drools
>  4 deps. You'll see clearly in .classpath -- Run "Driver". Let me know
>  if you have problems.
>
>  On 7/13/07, Mark Proctor <mproctor at codehaus.org> wrote:
>
> can you make an integration test for us? As we'll need to be easily able
>  to reproduce this. We'll add it to our code base and fix. We'll probably
>  add it as aprt of the MiscTest class:
> http://anonsvn.labs.jboss.com/labs/jbossrules/trunk/drools-compiler/src/test/java/org/drools/integrationtests/MiscTest.java
>
>
>  Aaron Dixon wrote:
>  > I am trying to sequentially perform two rules executions using two
>  > different classloaders in the same VM. I create completely new state
>  > for each execution, yet I still fail on the second execution. I
>  > believe this has to do with some internal static cached state that
>  > JBossRules is maintaining. A snippet of the code and exeception are
>  > shown in this email.
>  >
>  >    public void demo() throws Exception {
>  >        // Save original classloader
>  >        ClassLoader original =
>  > Thread.currentThread().getContextClassLoader();
>  >
>  >        // Create Classloader 1 with parent of original
>  >        FooClassLoader loader1 = new FooClassLoader(original);
>  >
> Thread.currentThread().setContextClassLoader(loader1);
>  >        testRules();
>  >
>  >        // Success so far...
>  >
>  >        // Create Classloader 2 with parent of original
>  >        FooClassLoader loader2 = new FooClassLoader(original);
>  >
> Thread.currentThread().setContextClassLoader(loader2);
>  >        testRules();
>  >
>  >        // Never make it to here.
>  >
>  >        // Restore
>  >
> Thread.currentThread().setContextClassLoader(original);
>  >    }
>  >
>  >    private void testRules() throws Exception {
>  >        PackageBuilder builder = new PackageBuilder();
>  >        Package pkg = buildPackage(new String[] { "Foo.drl" }, builder);
>  >        RuleBase base = RuleBaseFactory.newRuleBase();
>  >        base.addPackage(pkg);
>  >        StatelessSession session = base.newStatelessSession();
>  >        final ClassLoader loader =
>  > Thread.currentThread().getContextClassLoader();
>  >        Object inst = loader.loadClass("com.foo.Foo").newInstance();
>  >        session.execute(new Object[] { inst });
>  >    }
>  >
>  >
>  >
>  > Exception in thread "main" java.lang.ClassCastException:
>  >
> adixon.prototype.rules.classloader.demo.copy.FooShadowProxy
>  >     at
>  >
> org.drools.base.adixon.prototype.rules.classloader.demo.copy.Foo$getName.getValue(Unknown
>  >
>  > Source)
>  >     at
>  >
> org.drools.base.ClassFieldExtractor.getValue(ClassFieldExtractor.java:94)
>  >     at
>  >
> org.drools.base.evaluators.StringFactory$StringEqualEvaluator.evaluate(StringFactory.java:85)
>  >
>  >     at
>  >
> org.drools.rule.LiteralRestriction.isAllowed(LiteralRestriction.java:61)
>  >     at
>  >
> org.drools.rule.LiteralConstraint.isAllowed(LiteralConstraint.java:82)
>  >     at
> org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:121)
>  >     at
>  >
> org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:20)
>  >
>  >     at
>  >
> org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:159)
>  >     at
> org.drools.reteoo.Rete.assertObject(Rete.java:175)
>  >     at
>  >
> org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:190)
>  >     at
>  >
> org.drools.reteoo.ReteooWorkingMemory.doInsert(ReteooWorkingMemory.java:70)
>  >
>  >     at
>  >
> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:772)
>  >
>  >     at
>  >
> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:584)
>  >
>  >     at
>  >
> org.drools.reteoo.ReteooStatelessSession.execute(ReteooStatelessSession.java:63)
>  >
>  >     at
>  >
> adixon.prototype.rules.classloader.demo.copy.Driver.testRules(Driver.java:47)
>  >
>  >     at
>  >
> adixon.prototype.rules.classloader.demo.copy.Driver.go(Driver.java:33)
>  >     at
>  >
> adixon.prototype.rules.classloader.demo.copy.Driver.main(Driver.java:17)
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