A JDBC connection pool is a named group of JDBC connections to a database. These connections are created when the first request for connection is made on the pool when you start Sun Java System Web Server.
The JDBC connection pool defines the properties used to create a connection pool. Each connection pool uses a JDBC driver to establish a connection to a physical database at server start-up.
A JDBC-based application or resource draws a connection from the pool, uses it, and when no longer needed, returns it to the connection pool by closing the connection. If two or more JDBC resources point to the same pool definition, they will be using the same pool of connections at run time.
Creating connections in advance. The cost of establishing connections is moved outside of the code that is critical for performance.
Reusing connections. The number of times connections are created is significantly lowered.
Controlling the amount of resources a single application can use at any moment.
JDBC connection pools can be created and edited using the Administration interface, or by editing the attributes of the JDBCCONNECTIONPOOL element in the server.xml file. For more information, see the Sun Java System Web Server 6.1 SP9 Administrator’s Guide and the Sun Java System Web Server 6.1 SP9 Administrator’s Configuration File Reference, respectively.
Each defined pool is instantiated during web server startup. However, the connections are only created the first time the pool is accessed. It is recommended that you jump-start a pool before putting it under heavy load.