[rules-users] Help with MR3
Mark Proctor
mproctor at codehaus.org
Wed Jul 4 12:08:37 EDT 2007
actually I thought i tracked it down, was wrong. Anyway once the
RuleBase is built the "ObjectHashMap objectTypeNodes" in Rete should not
change....Only I things I can think of are:
1) Some how a thread is seeing a stale version of the map
2) the rulebase is getting updated while propagation is happening, maybe
combine with an issue from 1. In reality the rulebase addition should
obey the standard locking mechanism and stop this from happening.
3) The initial RuleBase hasn't finished building yet, and threads are
already being spun off to assert data.
I have a feeling its 3...
Mark
Mark Proctor wrote:
> ok, that might be it. We generate code in a singleton classloader, I
> suspect that each thread is generating its' own getters. I suspect
> that created singleton classloader is not getting GCd and releasing
> the perm gen. I'm not sure how to fix this. You can check this
> yourself by attaching a jprofiler instance (available for free trial)
> and looking at the object counts.
>
> I've tracked down the concurrency issue. The Rete node has a HashMap
> of ObjectTypeNodes that is built on the fly, that was global to the
> rulebase. I'll have to make it local to the working Memory. I'll fix
> that today.
>
> Mark
> s erel wrote:
>> Our server creates hundreds of stateful rule sessions concurrently.
>> Each created rule seesion is specific to a thread. We did not encounter
>> any memory problems with the previous version. As I've said,
>> it's difficult (actually, impossible) for me to provide you with a
>> self contained example
>> since the drl is complicated and contains dozens of complex objects.
>> However, I am ready to provide you with any information that can help
>> us in that manner.
>> I've also mentioned in the earlier threads the concurrency problem
>> I've encountered with AbstractHashTable.
>> Can this has something to do with it?
>>
>>
>> On 7/4/07, *Mark Proctor* <mproctor at codehaus.org
>> <mailto:mproctor at codehaus.org>> wrote:
>>
>> I don't beleive there is anything in 4.0 that is going to cause
>> such quick loss of permgen. Can you create a self contained
>> example that illustrates this behaviour? So we can reproduce this?
>>
>> Mark
>>
>> s erel wrote:
>>> We've tried to increase the permGen to 256mb. It did not help
>>> and the space run out really fast.
>>> Regarding MVEL, is turning code generation off something that
>>> can (or will) be done with a configuration parameter/factory
>>> method or do I need to track down all the places in the code?
>>>
>>> We did not experience such memory behavior with the previous
>>> version we used (3.06) when running the same tests.
>>> Bugs in 3.06 (no longer present in 4M3) are forcing us to upgrade.
>>>
>>> Is there another reason for such behaviour?
>>> Should we wait for release candidate?
>>>
>>>
>>> On 7/4/07, *Mark Proctor* <mproctor at codehaus.org
>>> <mailto:mproctor at codehaus.org>> wrote:
>>>
>>> increase your perm gen space,or use the MVEL dialect with
>>> code generation off.
>>>
>>>
>>> Mark
>>> s erel wrote:
>>>> Hello,
>>>>
>>>> During capacity tests we've received permGen OOM
>>>> exception. The occupied space in the permGen area increases
>>>> rapidly. Any opinions?
>>>>
>>>>
>>>> On 7/3/07, *s erel* <erelsagi at gmail.com
>>>> <mailto:erelsagi at gmail.com>> wrote:
>>>>
>>>> In our project we are creating a
>>>> StatefulRuleSession and saving it in a per-thread
>>>> context (i.e. Each thread has it's own
>>>> StatefulRuleSession):
>>>>
>>>> ruleServiceProvider.getRuleRuntime().createRuleSession(contextName,
>>>> properties, RuleRuntime.STATEFUL_SESSION_TYPE);
>>>>
>>>> When a thread session ends, we are calling release on
>>>> the previously created StatefulRuleSession.
>>>>
>>>>
>>>> Changing the following lines:
>>>>
>>>>
>>>> public abstract class AbstractHashTable
>>>>
>>>>
>>>> ...
>>>>
>>>> public Iterator iterator() {
>>>> // if ( this.iterator == null ) {
>>>> // this.iterator = new HashTableIterator(
>>>> this );
>>>> // }
>>>> //
>>>> // this.iterator.reset();
>>>> // return this.iterator;
>>>>
>>>> HashTableIterator iterator = new
>>>> HashTableIterator(this);
>>>> iterator.reset();
>>>>
>>>> return iterator;
>>>> }
>>>>
>>>> Seems to solve the problem I've encountered. What's
>>>> your opinion?
>>>>
>>>>
>>>> On 7/2/07, *Mark Proctor* <mproctor at codehaus.org
>>>> <mailto:mproctor at codehaus.org>> wrote:
>>>>
>>>> a working memory should be single threaded, so not
>>>> sure how this could be a race condition?
>>>>
>>>> Mark
>>>>
>>>> s erel wrote:
>>>>> I've done a little debugging. The code fails
>>>>> in the following segment:
>>>>>
>>>>> public static class HashTableIterator
>>>>> ...
>>>>> while ( this.entry == null ) {
>>>>> this.row++;
>>>>> if ( this.row == this.length ) {
>>>>> return null;
>>>>> }
>>>>> this.entry =
>>>>> this.table[this.row]; *// ---> index out of bounds
>>>>> exception*
>>>>> }
>>>>> }
>>>>>
>>>>> this.row has the same value as this.length despite
>>>>> the condition above it. Probably a race condition
>>>>> issue.
>>>>>
>>>>>
>>>>> On 7/2/07, *Mark Proctor* <mproctor at codehaus.org
>>>>> <mailto:mproctor at codehaus.org>> wrote:
>>>>>
>>>>> Not really :(
>>>>>
>>>>> In your situation I tend to keep removing
>>>>> rules and data while still making sure the
>>>>> error happens, to get it down to a minimum.
>>>>> Please do try, as this isn't an error that
>>>>> should happen. Or alterntaively you can open
>>>>> drools-core and drools-compiler in eclipse and
>>>>> execuse and debug this yourself - in your
>>>>> situation this might best. you can put in a
>>>>> breakpoint to listen for that particular
>>>>> exception.
>>>>>
>>>>> Mark
>>>>>
>>>>> s erel wrote:
>>>>>> It's hard for me to provide a self contained
>>>>>> project. The drl is long and uses several
>>>>>> business objects. It's the same drl as we've
>>>>>> been using for 306 minus the keyword changes.
>>>>>> Is there anything else i can check or provide
>>>>>> you in order to solve this matter.
>>>>>>
>>>>>> Thanks
>>>>>>
>>>>>> On 7/1/07, *Mark Proctor*
>>>>>> <mproctor at codehaus.org
>>>>>> <mailto:mproctor at codehaus.org>> wrote:
>>>>>>
>>>>>> Can you provide us a self contained
>>>>>> project which creates this error? Unless
>>>>>> we can recreate it, it will be very hard
>>>>>> to track it down. Please attach the
>>>>>> project to a jira and we'll make it a
>>>>>> priority.
>>>>>>
>>>>>> Mark
>>>>>> s erel wrote:
>>>>>>> Hello,
>>>>>>>
>>>>>>> I've just started integrating MR3 into
>>>>>>> my project (I've previously
>>>>>>> used 3.06). The drl compiles and
>>>>>>> everything seems fine, but during
>>>>>>> tests the following exception is thrown
>>>>>>> for time to time:
>>>>>>>
>>>>>>> java.lang.ArrayIndexOutOfBoundsException: 17
>>>>>>> at
>>>>>>> org.drools.util.AbstractHashTable$HashTableIterator.next(AbstractHashTable.java:250)
>>>>>>> at
>>>>>>> org.drools.reteoo.Rete$ObjectTypeConf.buildCache(Rete.java:434)
>>>>>>> at
>>>>>>> org.drools.reteoo.Rete$ObjectTypeConf.getObjectTypeNodes(Rete.java:425)
>>>>>>> at
>>>>>>> org.drools.reteoo.Rete.assertObject(Rete.java:172)
>>>>>>> at
>>>>>>> org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:190)
>>>>>>> at
>>>>>>> org.drools.reteoo.ReteooWorkingMemory$WorkingMemoryReteAssertAction.execute
>>>>>>> (ReteooWorkingMemory.java:163)
>>>>>>> at
>>>>>>> org.drools.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:1135)
>>>>>>> at
>>>>>>> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:781)
>>>>>>> at
>>>>>>> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:584)
>>>>>>> at
>>>>>>> org.drools.jsr94.rules.StatefulRuleSessionImpl.addObject(StatefulRuleSessionImpl.java:162)
>>>>>>>
>>>>>>> This only happens during high load tests.
>>>>>>> Can anyone help me?
>>>>>>>
>>>>>>> Thanks
>>>>>>>
>>>>>>> ------------------------------------------------------------------------
>>>>>>>
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>>>>>>
>>>>>>
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