void startOrKickThread() {
   if (sizeCalcThread == null) {
     log.debug2("Starting thread");
     sizeCalcThread = new SizeCalcThread();
     sizeCalcThread.start();
     sizeCalcThread.waitRunning();
   }
   sizeCalcSem.give();
 }
 void stopThread() {
   if (sizeCalcThread != null) {
     log.debug2("Stopping thread");
     sizeCalcThread.stopSizeCalc();
     sizeCalcThread = null;
   }
 }