public static void stop() {
   ReferenceQueueDaemon.INSTANCE.stop();
   FinalizerDaemon.INSTANCE.stop();
   FinalizerWatchdogDaemon.INSTANCE.stop();
   HeapTrimmerDaemon.INSTANCE.stop();
   GCDaemon.INSTANCE.stop();
 }
 // Invoked by the GC to request that the HeapTrimmerDaemon thread attempt to trim the heap.
 public static void requestHeapTrim() {
   synchronized (HeapTrimmerDaemon.INSTANCE) {
     HeapTrimmerDaemon.INSTANCE.notify();
   }
 }