In response to Chris Tierney’s recent article on max_reuse_connections in ColdFusion

This blog is in response to Chris Tierney’s recent article on max_reuse_connections in ColdFusion. Sorry Chris, but your blog truncated the server.xml entry, when I posted back. So, I am responding here.

Chris,

As mentioned on the blog, when Tomcat connector makes a connection with Tomcat server, it does not closes the connection even after it finished serving the request. Instead it keeps the connection active, so that for the next request, the same connection can be re-used. Also, the max value for the re-use connection is determined based on the number of sites configured with same CF server and the load on each site.

If you have connector created with “ALL” then the resources allocated, will be shared across connections. Whereas, the individual connectors would have there own dedicated connections. The reuse connection plays an important role in terms of performance, but the calculation has a little tweak to it. While creating individual connectors, we would prefer to keep the max_reuse_connections not go below 100 or 150 (if it’s a low traffic running site). For moderate traffic, the value may be 200/250. For a site running under high volume, the value may go around 500 or as higher, as needed.

Having said that, lets look at your scenario. You have 6 sites – 1 running under load and 5 with low traffic. When you create individual connectors, theoretically, these values can be set:-

Site with heavy traffic (only one site)

worker.cfusion.max_reuse_connections=500 worker.cfusion.connection_pool_size=800

Site with low traffic (rest five sites each)

worker.cfusion.max_reuse_connections=100 worker.cfusion.connection_pool_size=250

server.xml

<Connector port=”8012″ protocol=”AJP/1.3″ redirectPort=”8445″ tomcatAuthentication=”false” maxThreads=”2100″ connectionTimeout =”60000″> </Connector>

Note: calculation for maxThreads: 800+250*5=2050 (the value should be higher than this)

Similarly, when connector is created with “ALL”, theoretically, these values can be set:- worker.cfusion.max_reuse_connections=350 worker.cfusion.connection_pool_size=2100

server.xml

<Connector port=”8012″ protocol=”AJP/1.3″ redirectPort=”8445″ tomcatAuthentication=”false” maxThreads=”2100″ connectionTimeout =”60000″> </Connector>

Note: calculation for max_reuse_connections=connection_pool_size / {no of site}=2100/6=350.

Thus, in case of connector is created with “ALL”, the max_reuse_connections calculation is straight forward, but in case of “Individual” connector, its a bit tricky :-).