Why does the database connection break after ~1.5 hours of rest?

Question

Oracle

There is a VM on which there is a tornado server that works with Oracle, when the server starts everything is fine, it executes queries perfectly, but after ~ 1.5 hours of rest, the tornado gives an error " OperationalError: ORA-03114: not connected to ORACLE " . Why might this be happening?
The server itself works in conjunction with nginx, with the help of supervisor.
But it does not really matter, because the same story occurs when starting the server through the console without supervisor, and when starting the server without being tied to nginx. What could be the problem?
Python version - 2.7.5
Oracle client version - 11.2
cx_Oracle version - 5.1.3
tornado version - 4.3

Answer 1

Is the connection to the database permanent? If so, you need to find the setting responsible for terminating inactive connections by timeout. I don't remember where she is. See the listener.ora and sqlnet.ora docs for a start.

Answer 2

a) As an option, check the VM settings, what's with the network interface.
b) Dig towards alert.log, there are a lot of options for the appearance of 03114.