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From "Eickvonder Bjoern" <>
Subject AW: Connection Pooling
Date Tue, 14 Nov 2006 06:31:54 GMT

> <Resource name="jdbc/JSNDB" auth="Container" 
> 		type="javax.sql.DataSource"
>           maxActive="50" maxIdle="30" maxWait="10000"
>           removeAbandoned="true" 
> 		removeAbandonedTimeout="10" logAbandoned="true"
>           username="root" password="letmein2006" 
> 		driverClassName="com.mysql.jdbc.Driver"

> 1- does this mean that 50 connections will be made available 
> when the web app is loaded?

No, "maxActive" - as the name says - is only the maximum number of
connections. "initialSize" would create them on startup.

> 2- what happens if all the 50 connections are used up and 
> there are more db connection requests?

Your requesting thread would wait 10000 ms (defined by maxWait) for a
connection. If time is over an exception is thrown.

> 3- what about the maxIdle="30"; there cannot be more than 30 
> idle connections ?  

Yes, so in total for your configuration it means that your pool will
have 0 to 30 idle connections but is able to open up to 50 connections
if there is a really high load. The pool will - as far as I know - not
decrease idle connections in your configuration as
"timeBetweenEvictionRunsMillis" is not set.
Moreover connections that are not properly returned to the pool (by
closing it) will be considered abandoned after 10 seconds and then
closed/removed. Moreover this event will be logged out to the console
together with a stacktrace of the application code that failed to close
the connection. 

For more information see


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