Hi,
We are running a number of TomEE servers and most of them are using JDBC to
access Db2 for z/OS. The problem we see is that the connection pooling is
sending a lot of validation queries to the database server. I would say,
unneccesarily. To my knowledge there is a validation method called
Connection.isValid in all JDBC 4.0 based JDBC drivers. This moves the
responsibility to check if a connection is valid to the JDBC driver and it's up
to the driver development to implement an efficient way to check the validity.
The Oracle JDBC driver is doing the check by excuting an OPING lightweight RPC
call to the database server, and the IBM JDBC driver is doing the equivalent by
executing its very similar DRDA PING. This is the way to avoid unneccessary and
inefficient validation queries.
What about TomEE?
According to an example in the TomEE documentation we took away the
validationQuery and the configuration then looked like this.
testOnBorrow = true
testOnReturn = false
testWhileIdle = false
validationQuery =
That gave us the following exception.
OriginalError:java.sql.SQLException
Stacktrace: java.sql.SQLException: Failed to validate a newly established
connection.
at
org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:848)
at
org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:660)
at
org.apache.tomcat.jdbc.pool.ConnectionPool.getConnection(ConnectionPool.java:198)
at
org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:132)
Logically this is the result of the TomEE connection pooling to being unable to
use an empty value in validationQuery to do its own validation. Obviously, the
Connection.isValid is not used for the testOnBorrow.
So, what's my question?
I want to know whether the testOnBorrow can be set to false to get rid of the
validation query behaviour. And if so, will TomEE connection pooling make use
of the Connection.isValid method in the JDBC driver so that it is guaranteed to
get a valid connection?
Many thanks in advance, Len
Lennart Henang, Skandia
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