fix a crash during the update call

aman/sys/Worker.py

@@ -8,6 +8,12 @@ from aman.config.Airport import Airport
 class Worker(Thread):
     def __init__(self):
         Thread.__init__(self)
+        self.stopThread = None
+        self.icao = None
+        self.configuration = None
+        self.arrivalRoutes = None
+        self.updateLock = None
+        self.reportQueue = {}
 
     def __del__(self):
         self.release()
@@ -21,10 +27,18 @@ class Worker(Thread):
         self.reportQueue = {}
         self.start()
 
+    def acquireLock(self):
+        if None != self.updateLock:
+            self.updateLock.acquire()
+
     def release(self):
         self.stopThread = True
         self.join()
 
+    def releaseLock(self):
+        if None != self.updateLock:
+            self.updateLock.release()
+
     def run(self):
         counter = 0