SQLAlchemy MySQL error

When setting up the Paster server for my BuildAPI project, I used Sqlalchemy and MySQL to connect to the databases. I noticed that if I accessed a page on the server that connects to a database and then several hours later try to access the page again, I received a Server Error on the page.

Additionally, checking the paster.log file shows:

Error - <class 'sqlalchemy.exc.OperationalError'>: (OperationalError) (2006, 'MySQL server has gone away') 'SELECT builders.id, builders.name \nFROM builders \n LIMIT 50' ()

This error is a result of the database connections being specified to stay open forever and the server closing the connection after a period of time. There is an option called pool_recycle that should be set for MySQL connections, as noted in The Definitive Guide to Pylons book:

pool_recycle:

The length of time to keep connections open before recycling them. If not specified, the connections will stay open forever. This should be specified for MySQL in particular because servers typically close connections after eight hours, resulting in a “MySQL server has gone away” error.

Therefore, for example, in the project configuration I specified the pool_recyle as shown below:

sqlalchemy.your_db1.url = mysql://user:pass@localhost/your_db1

sqlalchemy.your_db2.url = mysql://user:pass@localhost/your_db2

sqlalchemy.pool_recycle = 3600