Re: java DB connection question

  Could be you have setup the db connection in tomcat and it is pooling it.
Looks like you are using JNDI to look it up so probably you are. So, in
addition to the database connection pool you also now have a webserver
connection pool. The webserver will release the connection after some time
(configurable) but holds on to it in case any other people hit the website
and request a connection to that database. Connection setup is
slow/expensive so pooling connections is an obvious optimization and done at
each tier/layer/level.

In short, your symptoms look like you are already doing best practice and
allowing the webserver to maintain a connection pool.

Best,
TimJowers


On 6/20/07, Jeoff Wilks <[email protected]> wrote:
>
> Use a servlet filter. You can attach the checked out connection to a
> request attribute for use in your struts actions, then the filter can make
> sure it's closed properly after the chain is done.
>
> On 6/20/07, Meichun Li <pcloudy2005-/[email protected]> wrote:
> >
> > Hi,
> >
> > What is the best practice in closing DB connection for
> > Struts Application with SQL server back end?
> >
> > I use Tomcat (tomcat 5.5.17) connection pooling. I
> > have an initial servlet  that does the JNDI look up
> > and  is loaded when tomcat starts.
> >
> > The servlet class:
> >
> > public class InitServlet extends HttpServlet {
> >
> >         protected static DataSource dataSource;
> >
> >         public void init() {
> >                 try {
> >                         String jndiName = getInitParameter("jndi.name");
> >                         DataSourceManager.getInstance(jndiName);
> >                 } catch (Exception e) {
> >                         e.printStackTrace();
> >                 }
> >
> >         }
> >
> > }
> >
> > And the DataSourceManager is:
> >
> > public class DataSourceManager {
> >
> >         private static DataSource ds = null;
> >
> >         private static DataSourceManager instance = null;
> >
> >         private DataSourceManager(String jndiName) throws
> > Exception {
> >                 createDataSource(jndiName);
> >         }
> >
> >         public static synchronized DataSourceManager
> > getInstance(String jndiName) throws Exception {
> >                 return (instance != null) ? instance : new
> > DataSourceManager(jndiName);
> >         }
> >
> >         private void createDataSource(String jndiName) throws
> > Exception {
> >                 Context initContext = new InitialContext();
> >                 Context envContext = (Context)
> > initContext.lookup("java:comp/env");
> >                 ds = (DataSource) envContext.lookup (jndiName);
> >
> >         }
> >
> >         public static DataSource getDataSource() throws
> > Exception {
> >                 return ds;
> >         }
> >
> >
> > }
> >
> >
> > I have two options:
> >
> > Option 1: In the struts Action execute method scope,
> > get the connection, pass the connection to the
> > business layer and DAO layer, and close the connection
> > in the execute finally block for example:
> >
> >         public ActionForward
> > executeAction(ActionMapping mapping, ActionForm form,
> > HttpServletRequest request, HttpServletResponse
> > response) throws Exception {
> >
> >                 DataSource
> > dataSource=DataSourceManager.getDataSource();
> >
> >                 Connetion connection= null;
> >
> >                 Try{
> >
> >                         Connection=dataSource.getConnection();
> >
> >                         // pass the connection to the DAO layer
> >                         …....
> >
> >                 } catch (SQLException e) {
> >
> >                 } finally {
> >                      if (connection != null) {
> >                                 try {
> >                                     connection.close();
> >                                 } catch (SQLException e) {
> >                                         ;
> >                                 }
> >                                 connection = null;
> >                         }
> >                 }
> >
> >
> >        I've tried this but sometimes I have connection
> > was closed error.
> >
> >
> > Option 2:   Get connection and close connection in
> > each method of DAO classes. Each thread/request to the
> > action invloves running several DAOs' method, so
> > serverl connections are open and closed by turn.  I
> > watched the SQL server process manager, it looks like
> > the connection  can't be returned to the pool
> > immediately even though the transaction is done, it
> > takes a while after that.
> >
> > Before I do any change, I will like to figure out what
> > is the best practise to handle the connection. Any
> > help will be appreciated.
> >
> > Thanks!
> > Maggie
> >
> >
> >
> >       ____________________________________________________________________________________
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