always try to close the connection before reconnecting.

poller-service.py

@@ -54,6 +54,11 @@ class DB:
 
     def connect(self):
         while True:
+            try:
+                self.conn.close()
+            except:
+                pass
+
             try:
                 if db_port == 0:
                     self.conn = MySQLdb.connect(host=db_server, user=db_username, passwd=db_password, db=db_dbname)