Magnus,
I agree with you and I changed my application from an open-close connection to
using a db pool. It works great, faster and the best of all, you can keep track of
how many connections you have + been used, timeouts, etc etc. Also, it helps on
our licensing scheme ;)
I used the DBPool that Dash uses. It is open-source and very reliable.... I didn't
used the whole framework, but just the DB connection pooling scheme...
http://www.working-dogs.com/dash/
Rodrigo
Magn�s ��r Torfason wrote:
> You're welcome, if it did you any good. I am not so well learned in the
> fine art of database Connections myself, so i'm trying to gather what
> information I can. But regarding the time they take to establish, I was
> just measuring it myself, and it looks to me as if it takes quite some time:
>
> OUTPUT:
> Connection created: 165
> Statement created: 166
> Query finished: 171
> rs.next() called: 171
> Bytes read: 188
>
> Connection created: 454
> Statement created: 459
> Query finished: 538
> rs.next() called: 538
> Bytes read: 658
>
> These are milliseconds, so in this case it took HALF A SECOND to create the
> Connection. That does add up.
>
> ps. Do you know of an open-source pool, I believe we will have to use it.
>
> CODE:
> long startTime = (new Date()).getTime();
> Class.forName ("oracle.jdbc.driver.OracleDriver");
> conn = DriverManager.getConnection ("jdbc:oracle:oci8:ncd", "dw302",
> "odd");
> conn.setAutoCommit (false);
> System.out.println( "Connection created: " + ((new Date()).getTime() -
> startTime) );
> stmt = conn.createStatement ();
> System.out.println( "Statement created: " + ((new Date()).getTime() -
> startTime) );
> rs = stmt.executeQuery (sqlSelect);
> System.out.println( "Query finished: " + ((new Date()).getTime() -
> startTime) );
> rs.next ();
> System.out.println( "rs.next() called: " + ((new Date()).getTime() -
> startTime) );
> OracleBlob blob = ((OracleResultSet)rs).getBlob (1);
> byte[] bytes = readBlob(conn, blob, 256);
> System.out.println( "Bytes read: " + ((new Date()).getTime() -
> startTime) );
>
> ----- Original Message -----
> From: Kirkdorffer, Daniel <[EMAIL PROTECTED]>
> To: 'Magn�s ��r Torfason' <[EMAIL PROTECTED]>
> Sent: Wednesday, September 29, 1999 7:29 PM
> Subject: RE: Re: Database Connections
>
> Magnus,
>
> You are right, the solution won't scale well. But some solutions don't need
> to scale. We simply won't ever have that problem. When that is a problem
> for another application, then we will see what we need to do. I'm sure the
> DBAs will have a change of heart if we could implement a pool that would
> maintain a limit on connections at any one time. BTW, database connections
> actually don't take that long to establish really, though. Thanks for the
> comments.
>
> Dan
>
> > ----------
> > From: Magn�s ��r Torfason[SMTP:[EMAIL PROTECTED]]
> > Sent: Wednesday, September 29, 1999 10:05 AM
> > To: Kirkdorffer, Daniel
> > Subject: Re: Re: Database Connections
> >
> > We are using that approach (each bean has its own connection), and that is
> > not scaling very well. Am I not correct in thinking that there are two
> > kinds of costs associated with Connections.
> >
> > 1) They take a long time to create
> > 2) The DBMS can only sustain a limited number of them at the same time
> >
> > To me it seems that the bean approach will very quickly lead to
> > overcrowding. We use Oracle8i and it grinds to a halt when the connection
> > count reaches 98. For performance reasons, 1 connection per user is very
> > restrictive (we use 4 Connection Beans per session), but even so, this
> > leads
> > to an absolute maximum of 98 users simultaneously. That is surely not
> > acceptable, so it seem to me that there are only two real options.
> > 1) Create Connections on the fly (regardless of the performance issues)
> > 2) Use a pool.
> >
> > The pool can easily be configured to time out, so that the connections die
> > if they have not been used for some time, so as to keep your DBA happy : )
> >
> > Magnus Torfason
> >
> > ----- Original Message -----
> > From: Kirkdorffer, Daniel <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Wednesday, September 29, 1999 6:01 PM
> > Subject: Re: Database Connections
> >
> >
> > > A new instance of the LoginBean will be created for each session. It
> > would
> > > be more appropriate for you to maintain your connection pool in another
> > > class, and for your LoginBean to ask that class object for a new
> > connection.
> > > You should also consider how best to manage the connection pool so that
> > it
> > > appropriately recovers from a server shutdown or the like.
> > >
> > > Another, simpler, approach would be to have each LoginBean establish and
> > > retain its own database connection. The price of doing this is really
> > only
> > > going to be once, at login. We looked at using connection pools, and
> > for
> > a
> > > small number of connections it really didn't save us much on systems
> > that
> > > will not need to be scaled up. In fact our DBAs said no to us even
> > using
> > > connection pools, and here they decide such things. They didn't want a
> > > bunch of open and unused connections sitting around.
> > >
> > > Probably rubs all the connection pool purists out there a little bit the
> > > wrong way, but hey!
> > >
> > > Cheers,
> > >
> > > Dan
> > > --
> > > Daniel Kirkdorffer
> > > NACN IS: 425-580-6225
> > > Sr. Consultant, Syllogistics LLC
> > > Email: [EMAIL PROTECTED]
> > > Web: http://www.syllogistics.com/
> > >
> > >
> > > > ----------
> > > > From: Nanduri Amarnath[SMTP:[EMAIL PROTECTED]]
> > > > Reply To: [EMAIL PROTECTED]
> > > > Sent: Wednesday, September 29, 1999 7:13 AM
> > > > To: [EMAIL PROTECTED]
> > > > Subject: Database Connections
> > > >
> > > > Hi everybody,
> > > > I am using a LoginBean as a Session Object in my JSP pages. The
> > > > LoginBean
> > > > takes user info and connects to a Database (where it validates the
> > > > username and
> > > > password). I am using a ConnectionPool to maintain a pool of
> > connections
> > > > to a
> > > > Database. I am creating the ConnectionPool inside the constructor of
> > the
> > > > LoginBean.
> > > >
> > > > My question is... If some 10 clients use my app.. will 10
> > > > ConnectionPools
> > > > be created ? If so, how can i overcome this to maintain only a single
> > > > connection
> > > > pool and have all my LoginBeans (sessions) access that pool.
> > > >
> > > > Forgive me if i am wrong...but i was under the impression that only a
> > > > single
> > > > LoginBean will be created on the server and all the JSP requests
> > access
> > > > that
> > > > bean. If this is the case, then how can i maintain sessions for all
> > the
> > > > different users ?
> > > >
> > > >
> > > > In servlets i used the init() method to create my ConnectionPool. Is
> > > > there
> > > > anything like this method, that i can use in the JSP to create my
> > > > ConnectionPool
> > > > ?
> > > >
> > > > Thank you very much for your feedback.
> > > >
> > > > Cheers,
> > > > Amar..
> > > >
> > > > [EMAIL PROTECTED]
> > > >
> > > >
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> > > >
> > >
> > >
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> > >
> >
>
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