[jira] [Commented] (FELIX-5028) ServiceFactory for components might return null

["Carsten Ziegeler (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FELIX-5028?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14739355#comment-14739355 ] 

Carsten Ziegeler commented on FELIX-5028:
-----------------------------------------

I'm not sure, but I think if in SingleComponentManager#getService( Bundle bundle, ServiceRegistration<S> serviceRegistration )
  the useCount would be increased as a first statement, it would be avoided that the instance and/or the component context are cleaned up through a concurrent ungetService.
If something fails in getService, we can decrement the counter, and if it gets to zero, clean up.

> ServiceFactory for components might return null
> -----------------------------------------------
>
>                 Key: FELIX-5028
>                 URL: https://issues.apache.org/jira/browse/FELIX-5028
>             Project: Felix
>          Issue Type: Bug
>          Components: Declarative Services (SCR)
>    Affects Versions: scr-2.0.0
>            Reporter: Carsten Ziegeler
>             Fix For: scr-2.0.2
>
>
> There seems to be an uneven handling of locking/status information in getService/ungetService of the service factory registered by the SingleComponentManager. (I didn't check the other factories)
> We have a concurrent get/ungetService for the same service. While the unget service uses a lock around decrementing the counter, incrementing the counter and other actions in getService are not using the lock. There is a partial lock there. 
> But this can lead to the problem that while the preconditions for getService are still fine, ungetService cleans up which then makes getService to return null.
> We have a huge app where we can reproduce the problem, I'll try to trim this down to a simple test case.



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