CFMX Query Timeout Gotcha

While doing some load testing a while back we came across a strange error while simulating the load that we were expecting. The simulated load had a large first peak, followed by a quieter period, followed by some more peaks.

During the load test we noticed a few query errors that we had never seen before, they related to the query connection timing out.

It turns out that the way CF times out datasource connections is slightly quirky as described below:

The other timeout setting in the CF Admin datasource detail page is just labeled as Timeout, with a paired setting for Interval. This timeout value is how long a connection should be idle before it is removed. So if a connection goes unused for this period of time, then the next time ColdFusion checks that connection it will be removed from the pool. The frequency that ColdFusion checks the connection idle time is set by the Interval setting. The default for the Timeout setting is 20 minutes and the Interval is 7 minutes, so every 7 minutes ColdFusion will check connections for that datasource and remove connections that have been idle for 20 minutes or more. The number of connections idle connections removed from the pool at each interval is hardcoded in ColdFusion to just five. Say you have 20 idle connections hanging around in a pool, this would require at least 28 minutes to be cleaned up.

Timeout (min)

The number of minutes that ColdFusion MX maintains an unused connection before destroying it.

Interval (min)

The time (in minutes) that the server waits between cycles to check for expired data source connections to close.

Cheers, Mark