[KARAF-6074] Race condition between the FeaturesService and FeatureDeploymentListener

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 4.2.2, 4.2.4
• Fix Version/s: 4.4.4, 4.3.10
• Component/s: karaf

Environment

Karaf 4.2.2 Windows 7 and Equinox

• Assignee: Jean-Baptiste Onofré
• Reporter: J. Brébec
• Created: 07/Jan/19 13:48
• Updated: 21/Jul/23 05:37
• Resolved: 21/Jul/23 05:37

Description

On the first start of a custom Karaf container (4.2.2), the logs shows a log of NPE in FeatureDeploymentListener.

After some analysis of this Exception, it's look like a race condition between the FeaturesService and the FeatureDeploymentListener :

1. The FeaturesService starts and launch a provisioning in another thread
2. a FeatureDeploymentListener is registered, and call bundleChanged for every bundle installed (the startup bundles)
3. It calls FeaturesService.state.requirements and get an empty map
4. Updating the root regions in the requirements map fails with an NPE
5. Some times later, the deployment task launched at step 1 is started, and FeaturesService.saveState() is called : state.requirements."root region" is initialised

The step 5 is executed in another thread, so it can happens before step 2 (and it works) or after, causing this NPE

Moreover, some methods in FeaturesService assume that state.requirements."root region" exists. There are probably others npe here.

 

14:37:55.668 ERROR [activator-1-thread-2] Unable to update deployed features for bundle: org.eclipse.osgi - 3.12.100.v20180210-1608
java.lang.NullPointerException: null
at org.apache.karaf.deployer.features.FeatureDeploymentListener.bundleChanged(FeatureDeploymentListener.java:247) [25:org.apache.karaf.deployer.features:4.2.2]
at org.apache.karaf.deployer.features.FeatureDeploymentListener.init(FeatureDeploymentListener.java:95) [25:org.apache.karaf.deployer.features:4.2.2]
at org.apache.karaf.deployer.features.osgi.Activator.doStart(Activator.java:52) [25:org.apache.karaf.deployer.features:4.2.2]
at org.apache.karaf.util.tracker.BaseActivator.run(BaseActivator.java:292) [25:org.apache.karaf.deployer.features:4.2.2]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:?]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:?]

Issue Links

• relates to: KARAF-6089 Deadlock with FeatureDeploymentListener
• links to: GitHub Pull Request #731