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Dimitris
Asked: 2011-07-06 21:54:48 +0800 CST

sqlalchemy fails to connect to db after server is idle for a few hours

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I have a fairly standard setup where the application server is separated by a firewall from the database server. The application is using sqlalchemy and the db is postgres.

The system works fine for a few hours, but once it remains idle for a long period it appears that the communication fails between the server and the db. The error log is:

WARNI [sqlalchemy.pool.QueuePool.0x...7310] [worker 26] Error closing cursor: cursor already closed

I set up the connection pool with the 'pool_recylce' setting set to 30mins, so that there are no connections lingering for more than 30 mins. The problem persists.

any ideas?

Update: I have posted the same question on stackoverflow and got an answer that worked. Have a look at https://stackoverflow.com/questions/6592137/sqlalchemy-fails-to-connect-to-db-after-server-is-idle-for-a-few-hours

firewall python postgresql

1 Answers

  1. I suggest to make sure that there are no active connections after half an hour of idling, e.g. with netstat -tpn. At least that will narrow down the problem to either (a) connections are still open so pool_recycle does not work as expected or (b) there are no open connections and the problem is elsewhere.

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