[rules-users] Class Cast Exception in Drools 4 Generated Accumulate Method
Hi Rules Users,
I'm experiencing an issue with a Drools 4.0.7 rule.
Here is a clip of the exception that is thrown:
Caused by: org.mvel.CompileException: cannot invoke method
at
org.mvel.optimizers.impl.refl.MethodAccessor.getValue(MethodAccessor.java:54)
at
org.mvel.optimizers.impl.refl.VariableAccessor.getValue(VariableAccessor.java:39)
at
org.mvel.ast.VariableDeepPropertyNode.getReducedValueAccelerated(VariableDeepPropertyNode.java:22)
at
org.mvel.ast.PropertyASTNode.getReducedValueAccelerated(PropertyASTNode.java:21)
at org.mvel.MVELRuntime.execute(MVELRuntime.java:90)
at
org.mvel.CompiledExpression.getValue(CompiledExpression.java:111)
at org.mvel.MVEL.executeExpression(MVEL.java:235)
at
org.drools.base.mvel.MVELConsequence.evaluate(MVELConsequence.java:48)
at
org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:554)
... 80 more
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor412.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at
org.mvel.optimizers.impl.refl.MethodAccessor.getValue(MethodAccessor.java:46)
... 88 more
Caused by: org.drools.RuntimeDroolsException:
java.lang.ClassCastException: com.demo.Rule_My_Rule_0$Accumulate0
at org.drools.rule.Accumulate.accumulate(Accumulate.java:131)
at
org.drools.reteoo.AccumulateNode.modifyTuple(AccumulateNode.java:352)
at
org.drools.reteoo.AccumulateNode.assertObject(AccumulateNode.java:248)
at
org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:318)
at
org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:162)
at org.drools.reteoo.Rete.assertObject(Rete.java:175)
at
org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:192)
at
org.drools.reteoo.ReteooWorkingMemory.doInsert(ReteooWorkingMemory.java:71)
at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:911)
at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:883)
at
org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java:67)
at
org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java:61)
... 92 more
Caused by: java.lang.ClassCastException:
com.demo.Rule_My_Rule_0$Accumulate0
at
com.demo.Rule_My_Rule_0Accumulate0Invoker.accumulate(Rule_My_Rule_0Accumulate0Invoker.java:43)
at org.drools.rule.Accumulate.accumulate(Accumulate.java:123)
... 103 more
The actually rule name and package are a lot longer, I changed them here
for brevity and because I don't believe the names themselves are relevant.
This exception is being thrown intermittently when this rule, which
contains an accumulate function is called. I say intermittently because
it does not happen every time the rule is run. As far as I can tell the
ClassCastExceptions only happens when the computer that the rules are
running on is under load.
A few more details before I post the rule itself. The rule base that I am
building consists of 2 drl files. Both of the files have the same package
declaration at the top. The 2 packages are built separately using
PackageBuilder then combined using RuleBase.addPackage() on both packages.
Also, I'm not sure if this is relevant, but this scenario takes place in
a web application where the two package objects are only built once (for
performance) but each user session creates a new RuleBase and adds the
packages. The individual sessions then create stateful sessions from the
rule base.
This is the rule that I believe is causing the issue.
rule My Rule
salience 50
dialect java
no-loop true
when
$module : Module( selected == false, required 1, $size :
required )
$list : ArrayList( )
from accumulate( PotentialMatch( module == $module, $slot
: slot ),
init( List result = new ArrayList(); ),
action( result.add($slot); ),
reverse( result.remove((Integer)$slot ); ),
result( result ) )
eval( countThem($list, $size) != $module.setMatchCount() )
then
modify( $module ) { setMatchCount(countThem($list, $size)) };
end
As I'm typing this I realize that there is another way to write this rule
using collect. I'm not sure why it was written this way, but since I have
already come this far, has anyone had any experience with the Drools 4
generated code throwing ClassCastExceptions?
Thanks,
Steve Ronderos___
rules-users mailing list
rules-users@lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
Re: [rules-users] Class Cast Exception in Drools 4 Generated Accumulate Method
Steve,
What versions of MVEL and Drools are you using?
Comments:
* You can not share packages between rulebases. You can share rulebases
among sessions. So, I strongly advise you to change your application to
build the rulebase once, and have the web sessions only create the rule
session every time... not the whole rulebase. Since packages have their own
classloaders and everytime you create a rulebase you merge such
classloaders, the problem might happen (CCE) exactly at the time you are
creating the rulebase concurrently. Drools 5 allows you to share packages,
although I still prefer to not do it and share only the rulebase.
* You can not use collect in this case, because you are creating a list of
$slot, not a list of PotentialMatch. Although, it is extremely easy to
create an accumulate function for that. Drools 5 includes 2 accumulate
functions: collectSet and collectList for that. If you want, just get the
class from Drools 5, fix the imports to use the classes from Drools 4 and
use it. Except for the imports you should not have any problem. Your rule
would look like:
*rule* My Rule
*salience* 50
*dialect* java
*no-loop* *true*
*when*
$module : Module( selected == *false*, required 1, $size :
required )
$list : List( )
*from* *accumulate*( PotentialMatch( module == $module,
$slot : slot ),
collectList( $slot ) )
*eval*( countThem($list, $size) != $module.setMatchCount() )
*then*
*modify*( $module ) { setMatchCount(countThem($list, $size)) };
*end*
* Finally, your eval looks odd to me, but anyway, don't have enough details
to advise you on that.
[]s
Edson
2009/6/23 Steve Ronderos steve.ronde...@ni.com
Hi Rules Users,
I'm experiencing an issue with a Drools 4.0.7 rule.
Here is a clip of the exception that is thrown:
Caused by: org.mvel.CompileException: cannot invoke method
at
org.mvel.optimizers.impl.refl.MethodAccessor.getValue(MethodAccessor.java:54)
at
org.mvel.optimizers.impl.refl.VariableAccessor.getValue(VariableAccessor.java:39)
at
org.mvel.ast.VariableDeepPropertyNode.getReducedValueAccelerated(VariableDeepPropertyNode.java:22)
at
org.mvel.ast.PropertyASTNode.getReducedValueAccelerated(PropertyASTNode.java:21)
at org.mvel.MVELRuntime.execute(MVELRuntime.java:90)
at
org.mvel.CompiledExpression.getValue(CompiledExpression.java:111)
at org.mvel.MVEL.executeExpression(MVEL.java:235)
at
org.drools.base.mvel.MVELConsequence.evaluate(MVELConsequence.java:48)
at
org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:554)
... 80 more
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor412.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at
org.mvel.optimizers.impl.refl.MethodAccessor.getValue(MethodAccessor.java:46)
... 88 more
Caused by: org.drools.RuntimeDroolsException: java.lang.ClassCastException:
com.demo.Rule_My_Rule_0$Accumulate0
at org.drools.rule.Accumulate.accumulate(Accumulate.java:131)
at
org.drools.reteoo.AccumulateNode.modifyTuple(AccumulateNode.java:352)
at
org.drools.reteoo.AccumulateNode.assertObject(AccumulateNode.java:248)
at
org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:318)
at
org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:162)
at org.drools.reteoo.Rete.assertObject(Rete.java:175)
at
org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:192)
at
org.drools.reteoo.ReteooWorkingMemory.doInsert(ReteooWorkingMemory.java:71)
at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:911)
at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:883)
at
org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java:67)
at
org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java:61)
... 92 more
Caused by: java.lang.ClassCastException:
com.demo.Rule_My_Rule_0$Accumulate0
at
com.demo.Rule_My_Rule_0Accumulate0Invoker.accumulate(Rule_My_Rule_0Accumulate0Invoker.java:43)
at org.drools.rule.Accumulate.accumulate(Accumulate.java:123)
... 103 more
The actually rule name and package are a lot longer, I changed them here
for brevity and because I don't believe the names themselves are relevant.
This exception is being thrown intermittently when this rule, which
contains an accumulate function is called. I say intermittently because it
does not happen every time the rule is run. As far as I can tell the
ClassCastExceptions only happens when the computer that
Re: [rules-users] Class Cast Exception in Drools 4 Generated Accumulate Method
Edson,
Thanks for the quick response!
I'm using Drools 4.0.7 and mvel 1.3.1
Thanks for the tip about packages and rulebases. I'll make sure to change
that in our code.
As far as changing the accumulate to collect, I can easily work around
that selector returning a list of PotentialMatches instead of Integers. I
made that change and have been unable to create the ClassCastException
since. I'm still not certain that the problem is resolved due to its
random nature, but I'm hoping that it is patched enough for now until we
can make the rulebase change you mentioned.
Thanks for the info about Drools 5. I'm currently in the process of
converting to Drools 5.
You're right the eval does look odd, but it is working for the time being.
This rule is in one of the first features I implemented using Drools, so
it is probably not done in the best way possible. I'll keep an eye on it
if I do not get this issue resolved some other way.
Thanks again!
Steve Ronderos
rules-users-boun...@lists.jboss.org wrote on 06/23/2009 11:09:48 AM:
[image removed]
Re: [rules-users] Class Cast Exception in Drools 4 Generated
Accumulate Method
Edson Tirelli
to:
Rules Users List
06/23/2009 11:29 AM
Sent by:
rules-users-boun...@lists.jboss.org
Please respond to Rules Users List
Steve,
What versions of MVEL and Drools are you using?
Comments:
* You can not share packages between rulebases. You can share
rulebases among sessions. So, I strongly advise you to change your
application to build the rulebase once, and have the web sessions
only create the rule session every time... not the whole rulebase.
Since packages have their own classloaders and everytime you create
a rulebase you merge such classloaders, the problem might happen
(CCE) exactly at the time you are creating the rulebase
concurrently. Drools 5 allows you to share packages, although I
still prefer to not do it and share only the rulebase.
* You can not use collect in this case, because you are creating a
list of $slot, not a list of PotentialMatch. Although, it is
extremely easy to create an accumulate function for that. Drools 5
includes 2 accumulate functions: collectSet and collectList for
that. If you want, just get the class from Drools 5, fix the imports
to use the classes from Drools 4 and use it. Except for the
imports you should not have any problem. Your rule would look like:
rule My Rule
salience 50
dialect java
no-loop true
when
$module : Module( selected == false, required 1, $size :
required )
$list : List( )
from accumulate( PotentialMatch( module == $module,
$slot : slot ),
collectList( $slot ) )
eval( countThem($list, $size) != $module.setMatchCount() )
then
modify( $module ) { setMatchCount(countThem($list, $size)) };
end
* Finally, your eval looks odd to me, but anyway, don't have enough
details to advise you on that.
[]s
Edson
2009/6/23 Steve Ronderos steve.ronde...@ni.com
Hi Rules Users,
I'm experiencing an issue with a Drools 4.0.7 rule.
Here is a clip of the exception that is thrown:
Caused by: org.mvel.CompileException: cannot invoke method
at org.mvel.optimizers.impl.refl.MethodAccessor.getValue
(MethodAccessor.java:54)
at org.mvel.optimizers.impl.refl.VariableAccessor.getValue
(VariableAccessor.java:39)
at
org.mvel.ast.VariableDeepPropertyNode.getReducedValueAccelerated
(VariableDeepPropertyNode.java:22)
at org.mvel.ast.PropertyASTNode.getReducedValueAccelerated
(PropertyASTNode.java:21)
at org.mvel.MVELRuntime.execute(MVELRuntime.java:90)
at
org.mvel.CompiledExpression.getValue(CompiledExpression.java:111)
at org.mvel.MVEL.executeExpression(MVEL.java:235)
at org.drools.base.mvel.MVELConsequence.evaluate
(MVELConsequence.java:48)
at org.drools.common.DefaultAgenda.fireActivation
(DefaultAgenda.java:554)
... 80 more
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor412.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke
(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.mvel.optimizers.impl.refl.MethodAccessor.getValue
(MethodAccessor.java:46)
... 88 more
Caused by: org.drools.RuntimeDroolsException:
java.lang.ClassCastException: com.demo.Rule_My_Rule_0$Accumulate0
at org.drools.rule.Accumulate.accumulate(Accumulate.java:131)
at org.drools.reteoo.AccumulateNode.modifyTuple
(AccumulateNode.java:352)
at org.drools.reteoo.AccumulateNode.assertObject
(AccumulateNode.java:248)
at
org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject
(CompositeObjectSinkAdapter.java
Re: [rules-users] Class Cast Exception in Drools 4 Generated Accumulate Method
Steve and all users of Drools 4,
Although earlier versions of Drools used mvel 1.3.1, in version 4.0.7 we
updated to mvel 1.3.9. There are several fixes from 1.3.1 to 1.3.9, so I
strongly suggest you all update. There are even newer versions of mvel
1.3.x, but the one I personally QA'd and found no problems was 1.3.9.
Updating is just a matter of replacing the old jar for the new jar in the
classpath. There are no API breaks or any other known problem.
[]s
Edson
2009/6/23 Steve Ronderos steve.ronde...@ni.com
Edson,
Thanks for the quick response!
I'm using Drools 4.0.7 and mvel 1.3.1
Thanks for the tip about packages and rulebases. I'll make sure to change
that in our code.
As far as changing the accumulate to collect, I can easily work around that
selector returning a list of PotentialMatches instead of Integers. I made
that change and have been unable to create the ClassCastException since.
I'm still not certain that the problem is resolved due to its random
nature, but I'm hoping that it is patched enough for now until we can make
the rulebase change you mentioned.
Thanks for the info about Drools 5. I'm currently in the process of
converting to Drools 5.
You're right the eval does look odd, but it is working for the time being.
This rule is in one of the first features I implemented using Drools, so it
is probably not done in the best way possible. I'll keep an eye on it if I
do not get this issue resolved some other way.
Thanks again!
Steve Ronderos
rules-users-boun...@lists.jboss.org wrote on 06/23/2009 11:09:48 AM:
[image removed]
Re: [rules-users] Class Cast Exception in Drools 4 Generated
Accumulate Method
Edson Tirelli
to:
Rules Users List
06/23/2009 11:29 AM
Sent by:
rules-users-boun...@lists.jboss.org
Please respond to Rules Users List
Steve,
What versions of MVEL and Drools are you using?
Comments:
* You can not share packages between rulebases. You can share
rulebases among sessions. So, I strongly advise you to change your
application to build the rulebase once, and have the web sessions
only create the rule session every time... not the whole rulebase.
Since packages have their own classloaders and everytime you create
a rulebase you merge such classloaders, the problem might happen
(CCE) exactly at the time you are creating the rulebase
concurrently. Drools 5 allows you to share packages, although I
still prefer to not do it and share only the rulebase.
* You can not use collect in this case, because you are creating a
list of $slot, not a list of PotentialMatch. Although, it is
extremely easy to create an accumulate function for that. Drools 5
includes 2 accumulate functions: collectSet and collectList for
that. If you want, just get the class from Drools 5, fix the imports
to use the classes from Drools 4 and use it. Except for the
imports you should not have any problem. Your rule would look like:
rule My Rule
salience 50
dialect java
no-loop true
when
$module : Module( selected == false, required 1, $size :
required )
$list : List( )
from accumulate( PotentialMatch( module == $module,
$slot : slot ),
collectList( $slot ) )
eval( countThem($list, $size) != $module.setMatchCount() )
then
modify( $module ) { setMatchCount(countThem($list, $size)) };
end
* Finally, your eval looks odd to me, but anyway, don't have enough
details to advise you on that.
[]s
Edson
2009/6/23 Steve Ronderos steve.ronde...@ni.com
Hi Rules Users,
I'm experiencing an issue with a Drools 4.0.7 rule.
Here is a clip of the exception that is thrown:
Caused by: org.mvel.CompileException: cannot invoke method
at org.mvel.optimizers.impl.refl.MethodAccessor.getValue
(MethodAccessor.java:54)
at org.mvel.optimizers.impl.refl.VariableAccessor.getValue
(VariableAccessor.java:39)
at
org.mvel.ast.VariableDeepPropertyNode.getReducedValueAccelerated
(VariableDeepPropertyNode.java:22)
at org.mvel.ast.PropertyASTNode.getReducedValueAccelerated
(PropertyASTNode.java:21)
at org.mvel.MVELRuntime.execute(MVELRuntime.java:90)
at
org.mvel.CompiledExpression.getValue(CompiledExpression.java:111)
at org.mvel.MVEL.executeExpression(MVEL.java:235)
at org.drools.base.mvel.MVELConsequence.evaluate
(MVELConsequence.java:48)
at org.drools.common.DefaultAgenda.fireActivation
(DefaultAgenda.java:554)
... 80 more
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor412.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke
(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585
