Webhost: eagerly free resources in customserver (#5512)

* Unref some locals that would live long for no reason.
* Limit scope of db_session in init_save.

WebHostLib/customserver.py

@@ -97,6 +97,7 @@ class WebHostContext(Context):
                         self.main_loop.call_soon_threadsafe(cmdprocessor, command.commandtext)
                         command.delete()
                     commit()
+            del commands
             time.sleep(5)
 
     @db_session
@@ -146,13 +147,13 @@ class WebHostContext(Context):
             self.location_name_groups = static_location_name_groups
         return self._load(multidata, game_data_packages, True)
 
-    @db_session
     def init_save(self, enabled: bool = True):
         self.saving = enabled
         if self.saving:
-            savegame_data = Room.get(id=self.room_id).multisave
-            if savegame_data:
-                self.set_save(restricted_loads(Room.get(id=self.room_id).multisave))
+            with db_session:
+                savegame_data = Room.get(id=self.room_id).multisave
+                if savegame_data:
+                    self.set_save(restricted_loads(Room.get(id=self.room_id).multisave))
             self._start_async_saving(atexit_save=False)
         threading.Thread(target=self.listen_to_db_commands, daemon=True).start()
 
@@ -304,6 +305,7 @@ def run_server_process(name: str, ponyconfig: dict, static_server_data: dict,
                     with db_session:
                         room = Room.get(id=ctx.room_id)
                         room.last_port = port
+                    del room
                 else:
                     ctx.logger.exception("Could not determine port. Likely hosting failure.")
                 with db_session:
@@ -322,6 +324,7 @@ def run_server_process(name: str, ponyconfig: dict, static_server_data: dict,
                 with db_session:
                     room = Room.get(id=room_id)
                     room.last_port = -1
+                del room
                 logger.exception(e)
                 raise
             else:
@@ -333,11 +336,12 @@ def run_server_process(name: str, ponyconfig: dict, static_server_data: dict,
                     ctx.save_dirty = False  # make sure the saving thread does not write to DB after final wakeup
                     ctx.exit_event.set()  # make sure the saving thread stops at some point
                     # NOTE: async saving should probably be an async task and could be merged with shutdown_task
-                    with (db_session):
+                    with db_session:
                         # ensure the Room does not spin up again on its own, minute of safety buffer
                         room = Room.get(id=room_id)
                         room.last_activity = datetime.datetime.utcnow() - \
                                              datetime.timedelta(minutes=1, seconds=room.timeout)
+                    del room
                     logging.info(f"Shutting down room {room_id} on {name}.")
                 finally:
                     await asyncio.sleep(5)