[jboss-dev-forums] [Javassist development Forum] - Advanced Classloader issue w Drools
I'm using Drools 4.0.0.12865MR3.
I have a rules file "Foo.drl" and class "com.foo.Foo" that I'd
like to load and execute rules against. However, I potentially need to load Foo in the
same VM using two different classloaders, CL1 and CL2. (The underlying use case is one in
which I'm doing dynamic class generation.)
Drools will fail with the below exception if I attempt to build afresh and execute my
rules in the same VM but loading the class with a second class loader. See code and
exception below.
NOTE. The first execution (using CL1) succeeds. It seems that Drools is maintaining some
kind of internal state/cache of some dynamically generated classes that causes it to fail
when loading using the second classloader.
| public void go() 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();
|
| // Create Classloader 2 with parent of original
| FooClassLoader loader2 = new FooClassLoader(original);
| Thread.currentThread().setContextClassLoader(loader2);
| testRules();
|
| // 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 });
| }
|
[1] Found foo : foo
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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