Resolved master and outstation not shutdown gracefully issue.

src/dnp3_python/dnp3station/master_new.py

@@ -582,12 +582,28 @@ def start(self):
         self.master.Enable()
 
     def shutdown(self):
-        # print("=======before master del self.__dict", self.__dict__)
+        """
+        Execute an orderly shutdown of the Master.
+        The debug messages may be helpful if errors occur during shutdown.
+
+        Expected:
+            channel state change: SHUTDOWN
+            ms(1667103120775) INFO    manager - Exiting thread (0)
+
+        Note:
+            Note: Don't use `self.manager.Shutdown()`, otherwise
+            "Process finished with exit code 134 (interrupted by signal 6: SIGABRT)"
+
+            Use `del self.master` instead of `self.master.Shutdown()`, otherwise
+            Process hanging
+        """
+
         sleep_before_master_shutdown = 2
         _log.info(f"Master station shutting down in {sleep_before_master_shutdown} seconds...")
         time.sleep(sleep_before_master_shutdown)  # Note: hard-coded sleep to avoid hanging process
-        del self.slow_scan
-        del self.fast_scan
+        # del self.master
         del self.master
-        del self.channel
-        del self.manager
+        # self.master.Shutdown()
+        self.channel.Shutdown()
+
+        # self.manager.Shutdown()

src/dnp3_python/dnp3station/outstation_new.py

@@ -225,26 +225,23 @@ def start(self):
 
     def shutdown(self):
         """
-            Execute an orderly shutdown of the Outstation.
+        Execute an orderly shutdown of the Outstation.
+        The debug messages may be helpful if errors occur during shutdown.
 
-            The debug messages may be helpful if errors occur during shutdown.
+        Expected:
+            ms(1667102887814) INFO    server - Operation aborted.
+            ms(1667102887821) INFO    manager - Exiting thread (0)
+
+        Note:
+            Note: Don't use `self.manager.Shutdown()`, otherwise
+            Process finished with exit code 134 (interrupted by signal 6: SIGABRT)
         """
-        # TODO: cannot shut down: see Outstation and master hang on shutdown #1 at
-        # https: // github.com / ChargePoint / pydnp3 / issues / 1
         time.sleep(2)  # Note: hard-coded sleep to avoid hanging process
         _outstation = self.get_outstation()
-        del _outstation
-        del self.channel
-        del self.log_handler
-        del self.outstation_application
-        del self.stack_config
-        del self.command_handler
-        del self.listener
-        del self.retry_parameters
-        # del self.manager
-
-        self.manager.Shutdown()  # Process finished with exit code 134 (interrupted by signal 6: SIGABRT)
-        # self.manager.__del__()  # Process finished with exit code 134 (interrupted by signal 6: SIGABRT)
+        _outstation.Shutdown()
+        self.channel.Shutdown()
+
+        # self.manager.Shutdown()
 
     @classmethod  # TODO: Justify the necessity to use class method
     def get_outstation(cls):