use better locking for the service startup/shutdown

owrx/service/__init__.py

@@ -61,7 +61,7 @@ class Js8ServiceOutput(ServiceOutput):
 
 class ServiceHandler(object):
     def __init__(self, source):
-        self.lock = threading.Lock()
+        self.lock = threading.RLock()
         self.services = []
         self.source = source
         self.startupTimer = None
@@ -124,6 +124,7 @@ class ServiceHandler(object):
         self.startupTimer.start()
 
     def updateServices(self):
+        with self.lock:
             logger.debug("re-scheduling services due to sdr changes")
             self.stopServices()
             if not self.source.isAvailable():
@@ -146,9 +147,6 @@ class ServiceHandler(object):
                 logger.debug("no services available")
                 return
 
-        with self.lock:
-            self.services = []
-
             groups = self.optimizeResampling(dials, sr)
             if groups is None:
                 for dial in dials: