Java Database Connectivity (JDBC)

Hello,

I hope that someone is able to help.

I have an application that is using jdbc (Oracle) to connect to a database. I'm creating an OracleDataSource, and trying to work out why "null" is returned from the Oracle JDBC drivers when I try and get a Connction from the database. I am using the "thin" drivers as these seem to work better than the "oci" ones.

I am fairly convinced that it is to do with the OracleDataSource running out of pooled connections.

Howerver the javadocs for javax.sql.DataSource and oracle.jdbc.pool.OracleDataSource do not indicate that "null" is a valid return value or why it would be returned. I am not getting a SQLException which I would expect if an error had occured (such as the pool running out).

I have been trawling the net trying to find reference to getConnection and I have pretty much drawn a blank, the only reference I have found is to use oracle.jdbc.pool.OracleConnectionCacheImpl and set a Cache Scheme as described here http://www.lc.leidenuniv.nl/awcourse/oracle/java.920/a96654/connpoca.htm#1065568 I think the behaviour I want is as described for DYNAMIC. But this method is deprecated and just says to use JDBC Implicit Connection Caching instead, which is what I think I am currently doing.

The code snippet below is how I am creating and setting up the OracleDataSource.

m_ODS = new OracleDataSource();
try
{
m_ODS.setDriverType("thin");
m_ODS.setPortNumber(1521);

m_ODS.setServerName(IP_ADDRESS);
m_ODS.setDatabaseName(DB_NAME);
m_ODS.setUser(USER);
m_ODS.setPassword(PASWORD);

m_ODS.setConnectionCachingEnabled(true);

m_ODS.setImplicitCachingEnabled(true);
m_ODS.setExplicitCachingEnabled(true);

final Properties prop = new Properties();

prop.setProperty("MinLimit", Integer.toString(MIN_CONNECTIONS));
prop.setProperty("MaxLimit", Integer.toString(MAX_CONNECTIONS));
prop.setProperty("InitialLimit", Integer.toString(MIN_CONNECTIONS));

prop.setProperty("MaxStatementsLimit", Integer.toString(25));

prop.setProperty("PropertyCheckInterval", "60");

prop.setProperty("ConnectionWaitTimeout", "10");

prop.setProperty("InactivityTimeout", "120");

prop.setProperty("AbandonedConnectionTimeout", "360");

m_ODS.setConnectionCacheProperties(prop);
}

I don't think that I am overly using the connection pool. I have 100 threads each trying to insert data twice a second (500 ms apart) on a pool size of 30 connections. I get a "null" connection after about 12 or so seconds. It is then intermittent after this.

Any help you can give would be really appreciated, even if it is a recommended way of dealing with the "null" return if it is expected behaviour.

Best regards,

Dan.