Thank you for your reply. What you say makes perfect sense. And as somebody
else already pointed out what I'm looking for is to implement the service
locator pattern (This will also benifit all our EBJs since they also perform
JNDI-lookups every single time). Thanks to you I don't even have to code it
! it'll be interesting to see how big a performance gain this will turn out
to be.
//linus
"Jason" <jptryon@tva.gov> wrote in message
news:471c5353.0309151219.47010be0@posting.google.c om...[color=blue]
> You're initializing everything each time. That equates directly to
> time. Now, I'm kind of assuming that you're doing this in a web
> implementation, so your milage may vary.
>
> Create a Singleton object that contains the DataSource object (only
> one for the whole app and shared across users). Initialize it either
> when the app starts up or say when the first user logs into the app
> after a restart. Then your calls to get the connection will look more
> like the second sample you provided.
>
>
-
> public void init(ServletConfig config) throws ServletException {
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> super.init(config) ;
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>
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> DatabaseResources dbResources = DatabaseResources.getInstance() ;
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>
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> Context context = null ;
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>
-
> try{
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> Hashtable environment = new Hashtable() ;
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> environment.put(Context.INITIAL_CONTEXT_FACTORY,
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> "com.ibm.websphere.naming.WsnInitialContextFactory") ;
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>
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> context = new InitialContext(environment) ;
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>
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> DataSource dbSource = (DataSource) context.lookup(
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> getServletContext().getInitParameter("dataSourceName")) ;
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>
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> dbResources.setDataSource(dbSource) ;
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> context.close() ;
-
> }
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> catch(Exception theException){
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> System.err.println(theException.toString() + " : Generated in "
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> + getClass().getName() + ".init() method") ;
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> theException.printStackTrace() ;
-
> }
-
> }
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>
-
>
-
> Now, here's the code for the DatabaseResources singleton object
-
>
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> /**
-
> * Gets the instance
-
> * @return Returns a DatabaseResources
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> */
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> public static DatabaseResources getInstance() {
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> if( instance == null )
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> instance = new DatabaseResources() ;
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> return instance;
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> }
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>
-
>
-
> Now, here's the code to get the connection. This exists in a
-
> superclass for all of my database access objects so this code only
-
> exists once in the app.
-
>
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> /**
-
> * Initialize the database connection with the provided user id &
-
> password
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> * @param String userID
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> * @param String password
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> * @throws SQLException
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> */
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> public void init(String userID, String password) throws SQLException
-
> {
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> DatabaseResources dbResources = DatabaseResources.getInstance() ;
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> DataSource dataSource = dbResources.getDataSource() ;
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> connection = dataSource.getConnection( userID, password ) ;
-
> }
-
>
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>
-
>
>
> Since all of my Classes that have to do database access ultimately
> subclass the class where init(String, String) is located, it's always
> available and makes getting the connection a single line call. One
> important note. init() is called inside a try{} and in the finally{}
> before we leave the method and after we've done the data operations I
> make the necessary calls to close the connections and such. This is
> very important if you don't want hanging connections which make your
> application server very unhappy.
> "Linus Nikander" <linus@nikander.net> wrote in message[/color]
news:<_ge9b.102346$zL.438@news1.bredband.com>...[color=blue][color=green]
> > Having recently load-tested the application we are developing I noticed[/color][/color]
that[color=blue][color=green]
> > one of the most expensive (time-wise) calls was my fetch of a[/color][/color]
db-connection[color=blue][color=green]
> > from the defined db-pool. At present I fetch my connections using :
> >
> >
> > private Connection getConnection() throws SQLException {
> > try {
> > Context jndiCntx = new InitialContext();
> > DataSource ds =
> > (DataSource)
> > jndiCntx.lookup("java:comp/env/jdbc/txDatasource");
> > return ds.getConnection();
> > } catch (NamingException ne) {
> > myLog.error(this.makeSQLInsertable("getConnection - could[/color][/color]
not[color=blue][color=green]
> > find connection"));
> > throw new EJBException(ne);
> > }
> > }
> >
> >
> > In other parts of the code, not developed by the same team, I've seen[/color][/color]
the[color=blue][color=green]
> > same task accomplished by :
> >
> > private Connection getConnection() throws SQLException {
> > return DriverManager.getConnection("jdbc:weblogic:jts:FTP ool");
> > }
> >
> > From the performance-measurements I made the latter seems to be much[/color][/color]
more[color=blue][color=green]
> > efficient (time-wise). To give you some metrics:
> >
> > The first version took a total of 75724ms for a total of 7224 calls[/color][/color]
which[color=blue][color=green]
> > gives ~ 11ms/call
> > The second version took a total of 8127ms for 11662 calls which gives
> > ~0,7ms/call
> >
> > I'm no JDBC guru som i'm probably missing something vital here. One
> > suspicion I have is that the second call first find the jdbc-pool and[/color][/color]
after[color=blue][color=green]
> > that makes the very same (DataSource)
> > jndiCntx.lookup("java:comp/env/jdbc/txDatasource") in order to fetch the
> > actual connection anyway. If that is true then my comparison is plain[/color][/color]
wrong[color=blue][color=green]
> > since one call is part of the second. If not, then the second version[/color][/color]
sure[color=blue][color=green]
> > seems a lot faster.
> >
> > Apart from the obvious performance-differences in the two above[/color][/color]
approaches,[color=blue][color=green]
> > is there any other difference one should be aware of[/color][/color]
(transaction-context[color=blue][color=green]
> > for instance) between the two ? Basically I'm working in an[/color][/color]
EJB-environment[color=blue][color=green]
> > on weblogic 7.0 and looking for the most efficient way to get hold of a
> > db-connection in code. Comments anyone ?
> >
> > //Linus Nikander -
linus@nikander.net[/color][/color]
