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https://issues.apache.org/jira/browse/OPENJPA-115?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12469604
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Craig Russell commented on OPENJPA-115:
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Yes, null checking is an expected requirement when dealing with weak 
references. If you can get a strong reference in a cleanup routine then it's ok 
to use it, because the fact that you have a strong reference will prevent 
garbage collection. 

If you get null from your weak reference, then the garbage collector has 
already done its job and by definition there can be nothing left for your 
routine to clean up.

> Bottleneck(s) with using OpenJPA in a Container-managed environment
> -------------------------------------------------------------------
>
>                 Key: OPENJPA-115
>                 URL: https://issues.apache.org/jira/browse/OPENJPA-115
>             Project: OpenJPA
>          Issue Type: Bug
>          Components: kernel
>            Reporter: Kevin Sutter
>         Assigned To: Kevin Sutter
>            Priority: Critical
>
> Running some benchmarks against OpenJPA using the Sun Java System (SunOne) 
> application server. Under load, we're not able to push the cpu to 100%. The 
> culprit seems to be the lock and synchronization processing within 
> AbstractBrokerFactory.newBroker(..). According to sections 5.9.1 and 5.9.2 in 
> the JPA specification, it looks like OpenJPA is attempting to do too much 
> management of the created EntityManagers. Within a Container-managed 
> environment, the Container takes care of the lifecycle of the EntityManagers. 
> So, there does not seem to be a need to do the findBroker(..) invocation, nor 
> is there a need to keep track of the created EntityManagers (_brokers) so 
> that they can be closed when the Factory is closed. 
> Once we have verified these changes, there may be others that are needed. 
> But, we have to get by this bottleneck first before going to the next 
> layer... 
> Kevin

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