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https://issues.apache.org/jira/browse/FELIX-2813?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12989101#comment-12989101
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Marcel Offermans commented on FELIX-2813:
-----------------------------------------
Take care that the service reference is fetched when an event is created, so
even if you delay processing the queue it might be that there's invalid events
in there.
> 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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