question: public void releaseExternalResources ( ) { if ( ! isClosed . get ( ) ) { logger . info ( "Releasing all ParallelClient resources... " ) ; ActorConfig . shutDownActorSystemForce ( ) ; httpClientStore . shutdown ( ) ; tcpSshPingResourceStore . shutdown ( ) ; taskManager . cleanWaitTaskQueue ( ) ; taskManager . cleanInprogressJobMap ( ) ; isClosed . set ( true ) ; logger . info ( "Have released all ParallelClient resources " + "(actor system + async+sync http client + task queue)" + "\nNow safe to stop your application." ) ; } else { logger . debug ( "NO OP. ParallelClient resources have already been released." ) ; } }
target:  Releases the external resources that this object depends on. You should not call this method if you still want to use the external resources (e.g. akka system, async http client store, thread pool for SSH/TCP) are in use by other objects.