I have odoo 12 in centOS7 server 

odoo service fails randomly and show some error messages like this

Started Odoo12.
Dec 05 10:37:02 ............... odoo12[8493]: Traceback (most recent call last):
Dec 05 10:37:02 ............... odoo12[8493]: File "/home/testodoo/odoo12/odoo-bin", line 5, in <module>
Dec 05 10:37:02 ............... odoo12[8493]: import odoo
Dec 05 10:37:02 ............... odoo12[8493]: File "/home/testodoo/odoo12/odoo/__init__.py", line 73, in <module>
Dec 05 10:37:02 ............... odoo12[8493]: import babel
Dec 05 10:37:02 ............... odoo12[8493]: ModuleNotFoundError: No module named 'babel'
Dec 05 10:37:02 ............... systemd[1]: odoo12.service: main process exited, code=exited, status=1/FAILURE
Dec 05 10:37:02 ............... systemd[1]: Unit odoo12.service entered failed state.
Dec 05 10:37:02 ............... systemd[1]: odoo12.service failed.

i already installed the module babel

 how this happens; please help me to fix this

and give tips to run odoo fast and efficiently without fail