Concurrency issues on Gather scenario

[hrosa]

Running load tests for Gather scenario unveils NPEs in media group actor:

11:38:05,550 ERROR [org.restcomm.connect.mscontrol.mms.MgcpMediaGroup] (RestComm-akka.actor.default-dispatcher-32) null: java.lang.NullPointerException
at org.restcomm.connect.mscontrol.mms.MgcpMediaGroup.notification(MgcpMediaGroup.java:214) [restcomm-connect.mscontrol.mms-8.0.0.issue1526-rms6-load-test.jar:8.0.0.issue1526-rms6-load-test]
at org.restcomm.connect.mscontrol.mms.MgcpMediaGroup.onReceive(MgcpMediaGroup.java:313) [restcomm-connect.mscontrol.mms-8.0.0.issue1526-rms6-load-test.jar:8.0.0.issue1526-rms6-load-test]
at akka.actor.UntypedActor$$anonfun$receive$1.applyOrElse(UntypedActor.scala:159) [akka-actor_2.10-2.1.2.jar:]
at akka.actor.ActorCell.receiveMessage(ActorCell.scala:425) [akka-actor_2.10-2.1.2.jar:]
at akka.actor.ActorCell.invoke(ActorCell.scala:386) [akka-actor_2.10-2.1.2.jar:]
at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:230) [akka-actor_2.10-2.1.2.jar:]
at akka.dispatch.Mailbox.run(Mailbox.scala:212) [akka-actor_2.10-2.1.2.jar:]
at akka.dispatch.ForkJoinExecutorConfigurator$MailboxExecutionTask.exec(AbstractDispatcher.scala:506) [akka-actor_2.10-2.1.2.jar:]
at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:262) [scala-library-2.10.1.jar:]
at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:975) [scala-library-2.10.1.jar:]
at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1478) [scala-library-2.10.1.jar:]
at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:104) [scala-library-2.10.1.jar:]

https://github.com/RestComm/Restcomm-Connect/blob/issue1526-rms6/restcomm/restcomm.mscontrol.mms/src/main/java/org/restcomm/connect/mscontrol/mms/MgcpMediaGroup.java#L214

Seems the media group is stopped (and originator cleaned) before the response comes from RMS.

Also there was one failed call during the test and it seems resources were not properly cleaned on RMS side as I see one UDP connection open on netstat.

Finally, netstat reveals a lot(!) of tcp connections in TIME_WAIT mode.

[hrosa]

Seems to have been fixed by #1614