[rules-users] Thread-deadlock when Negation Was Used and NullPointerException in Drools 5.0.1

[Andreas Kohn]

On Sep 11, 2009, at 9:21, Greg Barton <greg_barton at yahoo.com> wrote:

> Well, looking at CompositeClassLoader, it's already not completely  
> threadsafe even with the loadClass method synchronized. (This is  
> because loadClass calls fastFindClass, which iterates over the  
> classLoader ArrayList, which could be concurrently modified.)  So  
> the classLoader data strucure should be concurrent, and it's my  
> guess that removing the synchronization from  
> CompositeClassLoader.loadClass will be fine as long as the sub  
> ClassLoaders that actually do loading are threadsafe.
>

This is exactly the approach I used in JBRULES-2225, because not just  
was the locking broken, it also produced measurable contention in our  
application.
The fixed version behaved considerably better.

--
Andreas

> --- On Thu, 9/10/09, Dave McLoughlin <Dave.McLoughlin at openlogic.com>  
> wrote:
>
>> From: Dave McLoughlin <Dave.McLoughlin at openlogic.com>
>> Subject: [rules-users] Thread-deadlock when Negation Was Used and  
>> NullPointerException in Drools 5.0.1
>> To: rules-users at lists.jboss.org
>> Date: Thursday, September 10, 2009, 6:56 PM
>>
>>
>>
>>
>>
>> Thread-deadlock when Negation Was Used and
>> NullPointerException in Drools 5.0.1
>>
>>
>>
>>
>> We have a couple of issues we've
>> submitted to the issue tracker.
>>
>>
>>
>> JBRULES-2276 <https://jira.jboss.org/jira/browse/JBRULES-2276>
>>
>> JBRULES-2267 <https://jira.jboss.org/jira/browse/JBRULES-2267>
>>
>>
>>
>> While we are waiting for the core team to take a look we
>> wanted to see if anyone else has run into these issues and
>> has any advice for us.
>>
>>
>>
>> We have provided both our diagnosis of the issues and
>> fixes.  Our concern is whether we've taken the
>> right approach to the fixes and what the long term
>> ramifications are of the solutions.
>>
>>
>>
>> Any and all advice is welcome,
>>
>>
>>
>>
>>
>> Thanks,
>>
>>
>>
>>
>>
>>
>>
>> Dave
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
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>>
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