[KARAF-6329] NPE on shutdown

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 4.3.0, 4.2.5
• Fix Version/s: 4.3.0, 4.2.7
• Component/s: karaf
• Assignee: Jean-Baptiste Onofré
• Reporter: Sascha Vogt
• Created: 12/Jun/19 07:36
• Updated: 16/Jun/19 05:04
• Resolved: 16/Jun/19 05:04

Description

We found a NPE on shutdown:

2019-05-23T09:56:56.407+0000	 ERROR	 Felix	 FelixStartLevel	 [:]	 	 	 	 	 Bundle org.apache.karaf.features.core [11] EventDispatcher: Error during dispatch. (java.lang.NullPointerException)
java.lang.NullPointerException: null
	at org.apache.karaf.features.internal.osgi.Activator$2.removedService(Activator.java:306) ~[?:?]
	at org.apache.karaf.features.internal.osgi.Activator$2.removedService(Activator.java:292) ~[?:?]
	at org.osgi.util.tracker.ServiceTracker$Tracked.customizerRemoved(ServiceTracker.java:967) ~[?:?]
	at org.osgi.util.tracker.ServiceTracker$Tracked.customizerRemoved(ServiceTracker.java:870) ~[?:?]
	at org.osgi.util.tracker.AbstractTracked.untrack(AbstractTracked.java:341) ~[?:?]
	at org.osgi.util.tracker.ServiceTracker$Tracked.serviceChanged(ServiceTracker.java:909) ~[?:?]
	at org.apache.felix.framework.EventDispatcher.invokeServiceListenerCallback(EventDispatcher.java:990) ~[?:?]
	at org.apache.felix.framework.EventDispatcher.fireEventImmediately(EventDispatcher.java:838) [?:?]
	at org.apache.felix.framework.EventDispatcher.fireServiceEvent(EventDispatcher.java:545) [?:?]
	at org.apache.felix.framework.Felix.fireServiceEvent(Felix.java:4595) [?:?]
	at org.apache.felix.framework.Felix.access$000(Felix.java:106) [?:?]
	at org.apache.felix.framework.Felix$1.serviceChanged(Felix.java:420) [?:?]
	at org.apache.felix.framework.ServiceRegistry.unregisterService(ServiceRegistry.java:170) [?:?]
	at org.apache.felix.framework.ServiceRegistrationImpl.unregister(ServiceRegistrationImpl.java:144) [?:?]
	at org.apache.felix.framework.ServiceRegistry.unregisterServices(ServiceRegistry.java:241) [?:?]
	at org.apache.felix.framework.Felix.stopBundle(Felix.java:2661) [?:?]
	at org.apache.felix.framework.Felix.setActiveStartLevel(Felix.java:1391) [?:?]
	at org.apache.felix.framework.FrameworkStartLevelImpl.run(FrameworkStartLevelImpl.java:308) [?:?]
	at java.lang.Thread.run(Thread.java:748) [?:?]

Could it be a race condition, that even the tracker is closed it still gets a few removedService / addedService calls from another thread if the other thread already has a reference to the tracker once close from the first thread is called?

In that case, could a simple nullcheck avoid the issue?

Code: https://github.com/apache/karaf/blob/master/features/core/src/main/java/org/apache/karaf/features/internal/osgi/Activator.java#L306

Issue Links

• links to: GitHub Pull Request #877