Amichai Rothman created DOSGI-160:
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Summary: 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
Environment: Oracle JDK 1.7.0_17, Karaf 2.3.1, DOSGi 1.4.0 (installed
from Karaf feature)
Reporter: Amichai Rothman
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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