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https://issues.apache.org/jira/browse/FELIX-4597?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Xander Uiterlinden resolved FELIX-4597.
---------------------------------------
Resolution: Fixed
Resolved by returning a copy of the set on addHttpContext instead of the
original set.
> Race issue causing ConcurrentModificationException in
> org.apache.felix.http.whiteboard.internal.manager.ExtenderManager.add(ExtenderManager.java:111)
> -----------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: FELIX-4597
> URL: https://issues.apache.org/jira/browse/FELIX-4597
> Project: Felix
> Issue Type: Bug
> Components: HTTP Service
> Affects Versions: http-2.3.0
> Reporter: Xander Uiterlinden
> Assignee: Xander Uiterlinden
>
> Quite frequently when launching our application we're getting a
> ConcurrentModificationException, see the following stacktrace:
> java.util.ConcurrentModificationException
> at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429)
> at java.util.HashMap$KeyIterator.next(HashMap.java:1453)
> at
> org.apache.felix.http.whiteboard.internal.manager.ExtenderManager.add(ExtenderManager.java:111)
> at
> org.apache.felix.http.whiteboard.internal.tracker.HttpContextTracker.added(HttpContextTracker.java:37)
> at
> org.apache.felix.http.whiteboard.internal.tracker.HttpContextTracker.added(HttpContextTracker.java:24)
> at
> org.apache.felix.http.whiteboard.internal.tracker.AbstractTracker.addingService(AbstractTracker.java:36)
> at
> org.osgi.util.tracker.ServiceTracker$Tracked.customizerAdding(ServiceTracker.java:932)
> at
> org.osgi.util.tracker.ServiceTracker$Tracked.customizerAdding(ServiceTracker.java:864)
> at
> org.osgi.util.tracker.AbstractTracked.trackAdding(AbstractTracked.java:256)
> at org.osgi.util.tracker.AbstractTracked.track(AbstractTracked.java:229)
> at
> org.osgi.util.tracker.ServiceTracker$Tracked.serviceChanged(ServiceTracker.java:8
> This is caused by a race issue where one thread is adding HttpContext where
> another thread is adding a servlet for this context at the same time.
> Thread A:
> In ExtenderManager.addHttpContext(service, ref) the http context is added to
> the context manager which returns a collection of mappings. This collection
> is the actual collection as administered by the HttpContextHolder.
> In a for loop* on these mappings the mappings are registered with the
> HttpService.
> Collection<AbstractMapping> mappings =
> this.contextManager.addHttpContext(bundle, contextId, service);
> Thread B:
> When adding a servlet on the other thread, getHttpContext(mapping, ref) is
> called which calls getHttpContext(bundle, contextId, mapping). Here the
> HttpContextHolder is obtained by HttpContextHolder holder =
> this.idMap.get(id). After which holder.addMapping(mapping) is called. This
> addMapping is called while thread A is still in it's for loop iterating over
> the mappings.
> This requires synchronization. It would actually be nice to be able to
> synchronize on a particular HttpContext. This would require some method
> refactoring.
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