private static synchronized ExecutorService getExecutorService() {
    if (executorService == null) {
      LinkedBlockingQueue<Runnable> queue = new LinkedBlockingQueue<>();

      ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(
          THREAD_POOL_CORE_SIZE,
          THREAD_POOL_MAX_SIZE,
          THREAD_POOL_TIMEOUT,
          TimeUnit.MILLISECONDS,
          queue);

      threadPoolExecutor.allowCoreThreadTimeOut(true);
      executorService = threadPoolExecutor;
    }
    return executorService;
  }
Ensure that sync events are being processed.
ambari-server/src/main/java/org/apache/ambari/server/controller/internal/LdapSyncEventResourceProvider.java