diff --git a/ClusterController/ClusterController.py b/ClusterController/ClusterController.py
index 06dd3a6..80c974c 100644
--- a/ClusterController/ClusterController.py
+++ b/ClusterController/ClusterController.py
@@ -43,7 +43,7 @@ class SleepCompleteNotifier( ISleepCompleteNotifier ):
 		self.m_machineName = machineName
 		self.m_clusterController = clusterController
 	def onSleepComplete( self, bSleepSucceeded ):
-		logDebug('WakeUpCompleteNotifier::onWakeUpComplete : start')
+		logDebug('SleepCompleteNotifier::onSleepComplete : start')
 		self.m_clusterController.onMachineSleepComplete( self.m_machineName, bSleepSucceeded )
 
 def jouleToKwh( fEnergyInJoules ):
@@ -79,6 +79,8 @@ class ClusterController:
 		self.DELAY_BETWEEN_ENERGY_STATUS_LOGS = 60 # in seconds
 		self.m_iSessionId = None # session (run) identifier in database
 		self.m_webServer = WebServerThread(self)
+		self.m_bStop = False
+		self.m_bStopLock = threading.Lock() # to prevent concurrent access to m_bStop
 		
 	def getClusterStatus( self ):
 		return self.m_clusterStatus
@@ -104,9 +106,9 @@ class ClusterController:
 		#logDebug('ClusterController::onMachineSleepComplete : machine %s new len(self.m_machinesThatNeedWakeUp) = %d' % (machineName,len(self.m_machinesThatNeedWakeUp)) )		
 		self.m_machinesThatNeedSleepingLock.release()
 		if bSleepSucceeded:
-			logDebug('ClusterController::onMachineWakeUpComplete : removed %s from the list of machines that need waking up because it\'s now awake' % machineName)
+			logDebug('ClusterController::onMachineSleepComplete : removed %s from the list of machines that need sleeping because it\'s now sleeping' % machineName)
 		else:
-			logDebug('ClusterController::onMachineWakeUpComplete : removed %s from the list of machines that need waking up because it can\'t be put to sleep at the moment (eg a job just arrived)' % machineName)
+			logDebug('ClusterController::onMachineSleepComplete : removed %s from the list of machines that need sleeping because it can\'t be put to sleep at the moment (eg a job just arrived)' % machineName)
 		
 	def getNumPendingWakeUps( self ):
 		self.m_machinesThatNeedWakeupLock.acquire()
@@ -243,7 +245,7 @@ class ClusterController:
 			None
 		logInfo('ClusterController::run : cluster initial readings have completed')
 		startTime = time.localtime()
-		while True:
+		while not self.m_bStop:
 			currentTime = time.time()
 			#clusterStatus.m_nodesStatus['simpatix10'].dump()
 			if (not self.m_lastEnergyStatusLogTime) or (currentTime > (self.m_lastEnergyStatusLogTime +self.DELAY_BETWEEN_ENERGY_STATUS_LOGS)):