MySQL Bugs: #61707: MySQLNonTransientConnectionException: Connection.close() has already been called

Bug #61707	MySQLNonTransientConnectionException: Connection.close() has already been called
Submitted:	30 Jun 2011 13:22	Modified:	30 Jun 2011 15:29
Reporter:	sube singh	Email Updates:
Status:	Closed	Impact on me:	None
Category:	Connector / J	Severity:	S1 (Critical)
Version:	5.0.4	OS:	Solaris
Assigned to:		CPU Architecture:	Any
Tags:	Connection.close() has already been called, Connection.close() has already been called

Description:
Could you please suggest what is the reason for below given exception as soon as possible.

com.mysql.jdbc.exceptions.MySQLNonTransientConnectionException: Connection.close() has already been called. Invalid operation in this state.
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:888)
	at com.mysql.jdbc.Connection.getMutex(Connection.java:3640)
	at com.mysql.jdbc.Connection.setAutoCommit(Connection.java:5243)
	at com.mchange.v2.c3p0.impl.NewProxyConnection.setAutoCommit(NewProxyConnection.java:88

C3P0 setting
------------
   factory="org.apache.naming.factory.BeanFactory" 
                type="com.mchange.v2.c3p0.ComboPooledDataSource" 
                jdbcUrl="jdbc:mysql://localhost/mdsdb?autoReconnect=true"
                minPoolSize="10" 
                maxPoolSize="50" 
                acquireIncrement="5" 
                numHelperThreads="50"
                maxAdministrativeTaskTime="1200"
                maxIdleTime="2700" 
                maxIdleTimeExcessConnections="300"
                idleConnectionTestPeriod="600" 
                debugUnreturnedConnectionStackTraces="true"
                unreturnedConnectionTimeout="600

How to repeat:
xyz

What exact version of Connector/J, 5.1.x, do you use?

version: mysql-connector-java-5.0.4

Can you check with a newer version, 5.1.16?

I can try it. Could you please explain what is the root cause of problem?

Hi Sube.

It's a pools responsibility to check the connections it's dealing out to application and make sure they are still valid. In this case it certainly look slike C3P0 did not do it's job. Maybe there's some PING property you can set?

Hi,

Could you please suggest what is the best C3P0 setting for MySQL database with JDBC driver version 5.0.4?

Thanks,
Sube

If I changes attributes in C3P0,  MySQL db server throwing Apprent DeadLock exception.