Pierre De Rop created FELIX-3910:
------------------------------------

             Summary: Race conditions in DependencyManager
                 Key: FELIX-3910
                 URL: https://issues.apache.org/jira/browse/FELIX-3910
             Project: Felix
          Issue Type: Bug
          Components: Dependency Manager
    Affects Versions: dependencymanager-3.0.0
         Environment: jdk1.6, jdk1.7, linux fc16
            Reporter: Pierre De Rop


In a multi threaded context, where dependencies are injected concurrently from 
different threads, we  came across some exceptions which seem to take place 
from dependencymanager.

I have tried to reproduce the problems using a paxexam test which I will commit.
Not all exceptions are reproduced by the test case, but I think that the 
testcase really reproduces a problem. 

I also have a candidate patch, which I will submit to this jira issue.


Here are the exceptions we have seen:

first stacktrace seen:
===============

ERROR: Bundle test.dm [21] EventDispatcher: Error during dispatch. 
(java.lang.NullPointerException)
java.lang.NullPointerException
        at 
org.apache.felix.dm.impl.dependencies.ServiceDependencyImpl.addedService(ServiceDependencyImpl.java:481)
        at 
org.apache.felix.dm.tracker.ServiceTracker$Tracked.customizerAdded(ServiceTracker.java:1325)
        at 
org.apache.felix.dm.tracker.AbstractTracked.trackAdding(AbstractTracked.java:290)
        at 
org.apache.felix.dm.tracker.AbstractTracked.track(AbstractTracked.java:236)
        at 
org.apache.felix.dm.tracker.ServiceTracker$Tracked.serviceChangedHideAspects(ServiceTracker.java:1206)
        at 
org.apache.felix.dm.tracker.ServiceTracker$Tracked.serviceChanged(ServiceTracker.java:1101)
        at 
org.apache.felix.framework.util.EventDispatcher.invokeServiceListenerCallback(EventDispatcher.java:932)
        at 
org.apache.felix.framework.util.EventDispatcher.fireEventImmediately(EventDispatcher.java:793)
        at 
org.apache.felix.framework.util.EventDispatcher.fireServiceEvent(EventDispatcher.java:543)
        at org.apache.felix.framework.Felix.fireServiceEvent(Felix.java:4260)
        at org.apache.felix.framework.Felix.registerService(Felix.java:3275)
        at 
org.apache.felix.framework.BundleContextImpl.registerService(BundleContextImpl.java:346)
        at 
org.apache.felix.framework.BundleContextImpl.registerService(BundleContextImpl.java:320)
        at test.dm.race.RaceTest$RegistrationHelper$1.run(RaceTest.java:104)
        at 
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
        at 
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
        at java.lang.Thread.run(Thread.java:662)


second exceptions:
==============

ERROR: EventDispatcher: Error during dispatch. (java.lang.NullPointerException)
java.lang.NullPointerException
        at 
org.apache.felix.dm.impl.ComponentImpl.invokeCallbackMethod(ComponentImpl.java:686)
        at 
org.apache.felix.dm.impl.dependencies.ServiceDependencyImpl.invoke(ServiceDependencyImpl.java:704)
        at 
org.apache.felix.dm.impl.dependencies.ServiceDependencyImpl.invokeRemoved(ServiceDependencyImpl.java:666)
        at 
org.apache.felix.dm.impl.dependencies.ServiceDependencyImpl.removedService(ServiceDependencyImpl.java:520)
        at 
org.apache.felix.dm.tracker.ServiceTracker$Tracked.customizerRemoved(ServiceTracker.java:1351)
        at 
org.apache.felix.dm.tracker.AbstractTracked.untrack(AbstractTracked.java:359)
        at 
org.apache.felix.dm.tracker.ServiceTracker$Tracked.serviceChangedHideAspects(ServiceTracker.java:1285)
        at 
org.apache.felix.dm.tracker.ServiceTracker$Tracked.serviceChanged(ServiceTracker.java:1101)
        at 
org.apache.felix.framework.util.EventDispatcher.invokeServiceListenerCallback(EventDispatcher.java:878)
        at 
org.apache.felix.framework.util.EventDispatcher.fireEventImmediately(EventDispatcher.java:732)
        at 
org.apache.felix.framework.util.EventDispatcher.fireServiceEvent(EventDispatcher.java:662)
        at org.apache.felix.framework.Felix.fireServiceEvent(Felix.java:3587)
        at org.apache.felix.framework.Felix.access$000(Felix.java:40)
        at org.apache.felix.framework.Felix$1.serviceChanged(Felix.java:625)
        at 
org.apache.felix.framework.ServiceRegistry.unregisterService(ServiceRegistry.java:117)
        at 
org.apache.felix.framework.ServiceRegistrationImpl.unregister(ServiceRegistrationImpl.java:128)
        at org.apache.felix.dm.test.RaceTest$AFactory$2.run(RaceTest.java:151)
        at 
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
        at 
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
        at java.lang.Thread.run(Thread.java:662)



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