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https://issues.apache.org/jira/browse/DOSGI-160?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13631601#comment-13631601
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Amichai Rothman commented on DOSGI-160:
---------------------------------------
Thanks for the review and analysis :-)
Just a small correction regarding unregistering services in Activator.stop() -
as I understand it, the spec doesn't say you shouldn't unregister services in
stop(), just that it's optional:
{quote}
stop(BundleContext) – This method must undo all the actions of the
BundleActivator.start(BundleContext) method. However, it is unnecessary to
unregister services
or Framework listeners, because they must be cleaned up by the Framework anyway.
{quote}
So in theory you should undo everything (including service unregistration), but
in practice since the framework must make sure to clean up after bundles (even
if they misbehave), and will unregister services in any case, you can leave
that part out. In our case, I added it so that the code will be clearer - to me
it intuitively looked like a bug before I started digging in the spec...
To sum it up, the code is correct with or without the unregistration, and
putting a comment stating so explicitly also solves the maintainability issue,
so all is well :-)
> RemoteServiceAdmin shuts itself down during startup
> ---------------------------------------------------
>
> Key: DOSGI-160
> URL: https://issues.apache.org/jira/browse/DOSGI-160
> Project: CXF Distributed OSGi
> Issue Type: Bug
> Components: DSW
> Affects Versions: 1.4.0
> Environment: Oracle JDK 1.7.0_17, Karaf 2.3.1, DOSGi 1.4.0 (installed
> from Karaf feature)
> Reporter: Amichai Rothman
> Assignee: Christian Schneider
> Fix For: 1.5
>
> Attachments: fix_activator_config_and_sync_issues.diff
>
>
> Every once in a while (quite often) the service export fails. Looking through
> the logs, I found the message "RemoteServiceAdmin Implementation is shutting
> down now" - during Karaf startup! It appears that the RSA is started,
> services exported properly etc., but then it suddenly commits suicide a few
> moments later with no other error or indication of who/what initiated the
> shutdown or why.
> Further investigation shows the DSW Activator is getting a ConfigurationAdmin
> updated event with null configuration (according to the OSGi specs, the
> callback is guaranteed to be called - either with an existing configuration
> or with null if none is available). The current implementation of the
> callback stops the bundle, shutting down the service and printing the above
> log message, but when the configuration is null it does not start it back up,
> resulting in the observed behaviour.
> There's also a race condition in the class since from my understanding of the
> specs the updated callback is called asynchronously from a separate thread,
> and since it stops and possibly starts the bundle, this might cause the
> start/stop methods to be run concurrently and more than once (the bundle
> lifecycle start/stop along with the update-triggered start/stop).
> Finally, while debugging and attempting to fix this I came across a third
> related issue - when the bundle is indeed started up again in the updated
> method (e.g. if removing the null check or if a configuration is available),
> the start method then re-registers the ManagedService, which causes the
> updated method to be called again, which restarts the bundle again, etc. - in
> an infinite loop. In practice I saw the server hang with 100% CPU usage
> indefinitely, and in a later session with a debugger the loop was confirmed.
> Attached is a fix for the 3 related issues - when applied together everything
> seems to work as expected. I'm new to this project, so please correct
> anything I've missed.
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