public void checkForChange() {
      long currentValue = stats.getRawBits(stat);
      if (oldValueInitialized) {
        if (currentValue == oldValue) {
          return;
        }
      } else {
        oldValueInitialized = true;
      }
      oldValue = currentValue;
      listener.statValueChanged(getBitsAsDouble(currentValue));
    }
Checks to see if the value of the stat has changed. If it has then the local listener is
fired
geode-core/src/main/java/org/apache/geode/internal/statistics/GemFireStatSampler.java