linux pyodbc freeTDS mssql server stopped working after some time

Question

I have been successful in connecting to the sql server from and ubuntu machine using pyodbc/freeTDS

The setup works fine, but for some time after which i am getting the following error

[ERROR] (server)-('IM002', '[IM002] [unixODBC][Driver Manager]Data source name not found, and no default driver specified (0) (SQLDriverConnect)')

here is my config

odbc.ini

[SERVERONE]
Description="test"
Driver=/usr/lib/x86_64-linux-gnu/odbc/libtdsodbc.so
Servername=sqlserver
Database=DBONE

[SERVERTWO]
Description="test"
Driver=/usr/lib/x86_64-linux-gnu/odbc/libtdsodbc.so
Servername=sqlserver
Database=DBTWO

.freeTDS.conf

[global]
tds version = 8.0

[sqlserver]
host = <SERVER IP>
instance = R2TEST
port = 1070
tds version = 8.0
text size = 2000000

python module

class base(object):

    _connection = None


    def __init__(self):
        try:
            self._conn_string = ENV.DB.CONNSTRING
            logg.debug('using connection string %s'%self._conn_string)
            self._connection = pyodbc.connect(self._conn_string)
        except Exception:
            raise 
    def _refresh_conn(self):
        self._connection = None
        self._connection = pyodbc.connect(self._conn_string)

class getConf(base):

    def __init__(self):
        super(SamlConf,self).__init__()

    def getClientSamlConf(self, client):
        _query = "EXEC DBONE..getConfig '%s'" % (client)
        logg.info(_query)
        row = None
        try:
            _cursor = self._connection.cursor()
            _cursor.execute(_query)
            _row = _cursor.fetchone()
            if len(_row) >0 and _row[0]:
                logg.info(_row)                 
                row = ClienObj(_row)
            _cursor.commit()
            self._refresh_conn()
        except Exception,ex:
            import sys
            raise DatabaseCommunicationError('Communication to the database failed '), None, sys.exc_info()[2]
            return
        return row

The connection string used here is

DSN=SERVERONE;UID=user;PWD=password

I am suspecting that the way connections are handled here is the cause but am not sure.

Also, the setup starts working automatically after some time and the loops through it

working > not working > working

EDIT If this matter the other components of my stack are supervisor, gunicorn(gevent async) and virtualenv

EDIT 2

Another thing i have noticed is that the problem occurs when the application has no traffic for a long time