NPE when shuting down dispatcher with Scala 2.11

[ivantopo]

The following exception is thrown, as first reported on #34:

[ERROR] [06/05/2014 15:36:21.550] [services-scheduler-1] [akka.dispatch.Dispatcher] null
java.lang.NullPointerException
    at akka.instrumentation.DispatcherTracing.afterDispatcherShutdown(DispatcherTracing.scala:85)
    at akka.dispatch.Dispatcher.shutdown(Dispatcher.scala:101)
    at akka.dispatch.MessageDispatcher$$anon$2.run(AbstractDispatcher.scala:212)
    at akka.dispatch.MessageDispatcher$$anon$3.execute(AbstractDispatcher.scala:174)
    at akka.actor.LightArrayRevolverScheduler$TaskHolder.executeTask(Scheduler.scala:467)
    at akka.actor.LightArrayRevolverScheduler$$anon$8.executeBucket$1(Scheduler.scala:419)
    at akka.actor.LightArrayRevolverScheduler$$anon$8.nextTick(Scheduler.scala:423)
    at akka.actor.LightArrayRevolverScheduler$$anon$8.run(Scheduler.scala:375)
    at java.lang.Thread.run(Thread.java:744)

@adrien-aubel, could you please describe a bit more how you found this issue? does it happen right after starting your app? did you notice any way to reproduce the issue that we might isolate and test?

[ivantopo]

Sorry, duplicated of #37 and @dpsoft already fixed it on c985fe9.. there is a new snapshot with version 0.3.1-c03db365666030df9ab73ce1f087c9e8b1568f09 for Scala 2.11 containing this fix.

[adrien-aubel]

Great, thank you guys! Really appreciate it. I'll test that tomorrow morning (PST).

Cheers!

[adrien-aubel]

I tried to deploy the updated Kamon.io and got this exception at startup:

[ERROR] [06/06/2014 14:33:23.932] [threads-redis-client-akka.actor.default-dispatcher-5] [akka://threads-redis-client/system/IO-TCP/selectors] null
akka.actor.ActorInitializationException: exception during creation
at akka.actor.ActorInitializationException$.apply(Actor.scala:164)
at akka.actor.ActorCell.create(ActorCell.scala:596)
at akka.actor.ActorCell.invokeAll$1_aroundBody2(ActorCell.scala:456)
at akka.actor.ActorCell$AjcClosure3.run(ActorCell.scala:1)
at org.aspectj.runtime.reflect.JoinPointImpl.proceed(JoinPointImpl.java:149)
at akka.instrumentation.ActorSystemMessagePassingTracing$$anonfun$aroundSystemMessageInvoke$1.apply(ActorSystemMessagePassingTracing.scala:61)
at kamon.trace.TraceRecorder$.withTraceContext(TraceRecorder.scala:66)
at akka.instrumentation.ActorSystemMessagePassingTracing.aroundSystemMessageInvoke(ActorSystemMessagePassingTracing.scala:61)
at akka.actor.ActorCell.invokeAll$1(ActorCell.scala:1)
at akka.actor.ActorCell.systemInvoke(ActorCell.scala:478)
at akka.dispatch.Mailbox.processAllSystemMessages(Mailbox.scala:263)
at akka.dispatch.Mailbox.run(Mailbox.scala:219)
at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:393)
at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at akka.util.Reflect$.instantiate(Reflect.scala:66)
at akka.actor.ArgsReflectConstructor.produce(Props.scala:349)
at akka.actor.Props.newActor(Props.scala:249)
at akka.actor.ActorCell.newActor(ActorCell.scala:552)
at akka.actor.ActorCell.create(ActorCell.scala:578)
... 15 more
Caused by: java.lang.NullPointerException
at akka.actor.ActorSystemImpl.findExtension(ActorSystem.scala:697)
at akka.actor.ActorSystemImpl.registerExtension(ActorSystem.scala:706)
at akka.actor.ExtensionId$class.apply(Extension.scala:79)
at kamon.metrics.Metrics$.apply(MetricsExtension.scala:97)
at kamon.Kamon$.apply(Kamon.scala:31)
at akka.instrumentation.DispatcherTracing.afterDispatcherStartup(DispatcherTracing.scala:55)
at akka.dispatch.Dispatcher$LazyExecutorServiceDelegate.executor$lzycompute(Dispatcher.scala:44)
at akka.dispatch.Dispatcher$LazyExecutorServiceDelegate.executor(Dispatcher.scala:44)
at akka.dispatch.ExecutorServiceDelegate$class.execute(ThreadPoolBuilder.scala:212)
at akka.dispatch.Dispatcher$LazyExecutorServiceDelegate.execute(Dispatcher.scala:43)
at akka.dispatch.Dispatcher.executeTask(Dispatcher.scala:76)
at akka.dispatch.MessageDispatcher.unbatchedExecute(AbstractDispatcher.scala:145)
at akka.dispatch.BatchingExecutor$class.execute(BatchingExecutor.scala:113)
at akka.dispatch.MessageDispatcher.execute(AbstractDispatcher.scala:85)
at akka.util.SerializedSuspendableExecutionContext.attach(SerializedSuspendableExecutionContext.scala:75)
at akka.util.SerializedSuspendableExecutionContext.execute(SerializedSuspendableExecutionContext.scala:76)
at akka.io.SelectionHandler$ChannelRegistryImpl.<init>(SelectionHandler.scala:151)
at akka.io.SelectionHandler.<init>(SelectionHandler.scala:234)
... 24 more

The application seems to work fine, but I'd like to have your opinion on this exception before using it in production.

[dpsoft]

close related to #37