@VisibleForTesting
  public void waitForQueuedCommands() throws InterruptedException {
    while (itemsInProgress.get() > 0) {
      synchronized (itemsInProgress) {
        itemsInProgress.wait(100L);
      }
    }
  }
Whether to only update stats that already exist and are out of date.
ql/src/java/org/apache/hadoop/hive/ql/stats/StatsUpdaterThread.java