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https://issues.apache.org/jira/browse/FELIX-335?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Felix Meschberger updated FELIX-335:
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Attachment: ConfigAdmin.FELIX-335_2.patch
Thanks for the feedback.
I went over the code again and again found some issues:
(1) It seems that when a ManagedService is registered and a new configuration
is found, the configuration is immediately bound to the ManagedService. I
assume, this is probably wrong. So I added precaution to not bind brand new
configuration to the ManagedService.
(2) The FilePersistenceManager does not seem to act very well in multithreaded
situations: A configuration file is directly written and thus may be read at
the same time and hence returning nothing at. I added synchronization to the
load and store methods to prevent same-time access to files as well as have the
store method write to a temporary file which is renamed when done.
Attached, find a new patch, which is complete in a sense, that it includes the
changes of yesterday.
Sorry to misuse you as the testbed for this... But I cannot currently come up
with a good muli-threaded test case.
> Configuration Admin updates with empty properties and throws
> NullPointerExceptions due to race condition
> --------------------------------------------------------------------------------------------------------
>
> Key: FELIX-335
> URL: https://issues.apache.org/jira/browse/FELIX-335
> Project: Felix
> Issue Type: Bug
> Components: Configuration Admin
> Reporter: Karl Pauls
> Assignee: Felix Meschberger
> Attachments: ConfigAdmin.FELIX-335.patch,
> ConfigAdmin.FELIX-335_2.patch, empty-properties.patch
>
>
> There appears to be a race condition in the configuration admin that allows
> managed services to get updated with empty properties (but not null).
> Furthermore, due to the same bug NullPointerExceptions appear under heavy
> load.
> Fortunately, I think I was able to isolate the bug. The issue is that
> configurations are persisted when created but before they are initialized
> (i.e., given a configuration). If during this window a new ManagedService
> appears it gets updated with an empty Dictionary. Likewise, if the
> configuration is re-read after such an update attempt it does not have a pid
> which causes the null pointer exceptions.
> The fix seems to be rather simple (unless I'm missing something :-) but took
> me some time to figure out.
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