protected void ensureEventProcessor() {

    if (!processingEvents) {
      synchronized (eventQueue) {
        if (!processingEvents) {
          processingEvents = true;
          getExecutorService().submit(new Runnable() {
            @Override
            public void run() {
              processSyncEvents();
            }
          });
        }
      }
    }
  }
Ensure that sync events are being processed.
ambari-server/src/main/java/org/apache/ambari/server/controller/internal/LdapSyncEventResourceProvider.java