Question

I’m using tomcat 7 and the tomcat jdbc connection pool to dish out mysql connections.

During night times we don’t have any activity so all connections become idle for longer than 8 hours and are dropped by mysql. (mysql’s wait_timeout default).

We use the following pool configuration:

<Resource name="jdbc/dbName"
        auth="Container"
        factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
        type="javax.sql.DataSource"
        maxActive="50"
        maxIdle="30"
        maxWait="5000"
        driverClassName="com.mysql.jdbc.Driver"
        validationQuery="SELECT 1"
        testOnBorrow="true"
        testWhileIdle="true"
        timeBetweenEvictionRunsMillis="10000"
        removeAbandoned="true"
        removeAbandonedTimeout="60"
        logAbandoned="true"
        username="xxx"
        password="xxx"
        url="jdbc:mysql://host:3306/xxx"/>

I was expecting the EvictionPolicy to remove idle connections way before they ever get closed by MySql. Somehow after one day we get the following exception:

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.Connection was implicitly closed by the driver.

I guess this problem should be something the jdbc connection pool can fix, but there are many configuration properties and I haven’t used this pool before. Anybody got a good set of properties to configure the pool to not dish out closed connections?

Kind regards,

Albert

Answer 1

Solved it. Turned out it wasn’t a pooling problem after all. We were using squeryl and lift together which isn’t a happy combi (just yet). Connections got closed before returned to the pool.
Ditching lift’s DB connection management in favor of squeryl’s solved it.