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https://issues.apache.org/jira/browse/FELIX-2813?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12989180#comment-12989180
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Felix Meschberger commented on FELIX-2813:
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Yes, the ConfigurationEvent is actually generated immediately before sending it 
out. So just enqueuing the task to send the event is save.

> NPE in UpdateThread when updating a configuration right after 
> ConfigurationAdmin service starts
> -----------------------------------------------------------------------------------------------
>
>                 Key: FELIX-2813
>                 URL: https://issues.apache.org/jira/browse/FELIX-2813
>             Project: Felix
>          Issue Type: Bug
>          Components: Configuration Admin
>            Reporter: Marcel Offermans
>
> When you:
> 1) register as a configuration listener
> 2) wait for the ConfigurationAdmin service to start
> 3) upon start, immediately create a new configuration and update its 
> properties
> You (sometimes) get a NPE in the UpdateThread because there is a race 
> condition in the codebase:
> a) ConfigurationManager.java:1818 will invoke getServiceReference() which 
> uses the service registration to get to the reference
> b) ConfigurationManager.java:242 registers the service and assigns the 
> registration to 'configurationAdminRegistration'
> First of all, the call to registerService in line 242 will already trigger 
> service listeners and trackers to invoke callbacks before this call returns, 
> so 'configurationAdminRegistration' will still be null. Furthermore, there is 
> no synchronization, the member is not volatile, so we need to make sure this 
> value is really written before any configuration events are created under a) 
> (now the thread doing that is started way before the service is registered).
> I will commit a test that shows the exception, but since it happens in a 
> thread I cannot "catch" it won't show up as a failed test.

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