I am getting below error while starting odoo-8. Can any one help me please?

2015-10-22 10:18:51,144 1545 INFO ? openerp: OpenERP version 8.0

2015-10-22 10:18:51,144 1545 INFO ? openerp: addons paths: ['/opt/Store/addons/8.0', u'/opt/odoo/OERP8/openerp/addons', u'/o$

2015-10-22 10:18:51,144 1545 INFO ? openerp: database hostname: localhost

2015-10-22 10:18:51,144 1545 INFO ? openerp: database port: 5432

2015-10-22 10:18:51,144 1545 INFO ? openerp: database user: odoo

2015-10-22 10:18:51,239 1545 INFO ? openerp.service.server: Evented Service (longpolling) running on 0.0.0.0:7069

2015-10-22 10:18:53,159 1545 INFO ? openerp.addons.report.models.report: Will use the Wkhtmltopdf binary at /usr/bin/wkhtmlt$

2015-10-22 10:18:53,159 1545 INFO ? openerp.addons.bus.bus: Bus.loop listen imbus on db postgres

2015-10-22 10:18:53,308 1545 INFO ? openerp.http: HTTP Configuring static files

2015-10-22 10:21:00,474 1545 ERROR ? openerp.addons.bus.bus: Bus.loop error, sleep and retry

Traceback (most recent call last):

File "/opt/odoo/OERP8/addons/bus/bus.py", line 136, in run

self.loop()

File "/opt/odoo/OERP8/addons/bus/bus.py", line 114, in loop

with openerp.sql_db.db_connect('postgres').cursor() as cr:

File "/opt/odoo/OERP8/openerp/sql_db.py", line 575, in cursor

return Cursor(self.__pool, self.dbname, self.dsn, serialized=serialized)

File "/opt/odoo/OERP8/openerp/sql_db.py", line 181, in __init__

self._cnx = pool.borrow(dsn)

File "/opt/odoo/OERP8/openerp/sql_db.py", line 464, in _locked

return fun(self, *args, **kwargs)

File "/opt/odoo/OERP8/openerp/sql_db.py", line 526, in borrow

result = psycopg2.connect(dsn=dsn, connection_factory=PsycoConnection)

File "/usr/lib/python2.7/dist-packages/psycopg2/__init__.py", line 179, in connect

connection_factory=connection_factory, async=async)

File "build/bdist.linux-x86_64/egg/psycogreen/gevent.py", line 29, in gevent_wait_callback

state = conn.poll()

OperationalError: asynchronous connection failed