public GenericHelixController(PipelineRegistry registry) {
_paused = false;
_registry = registry;
_lastSeenInstances = new AtomicReference<Map<String, LiveInstance>>();
_lastSeenSessions = new AtomicReference<Map<String, LiveInstance>>();
_eventQueue = new ClusterEventBlockingQueue();
_eventThread = new ClusterEventProcessor();
_eventThread.setDaemon(true);
_eventThread.start();
_cache = new ClusterDataCache();
}