may i know why connections shouldn't be built in the init method . how do
you manage connection pooling otherwise ??
> ----------
> From: Varalakshmi Allamaraju[SMTP:[EMAIL PROTECTED]]
> Reply To: A mailing list for discussion about Sun Microsystem's Java
> Servlet API Technology.
> Sent: Monday, May 22, 2000 4:51 PM
> To: [EMAIL PROTECTED]
> Subject: Re: JDBC connection problem
>
> - Never ever try to create connections objects in the constructor/init
> methods of a servlet. Please refer to any good material on how
> connections are created, and their relation to transactions!
>
> - You mention that you make sure that only one request can access the
> connectoon variable at a time. I don't see any such magic code in your
> code.
>
> - There have been several discussions on how and where to create
> connections. Look into the archives. There is also an article in the JDJ
> March issue.
>
>
> zengjj wrote:
> >
> > Hi there,
> > Now I use the javawebserver2.0 to develope a three-tier Database
> Applications.
> > The client want to query the database in the applet through our servlet.
> > Because it usually take serveral minuters to build a connection, so I
> use a global Connection variable,
> > this connection will be built in the init function.
> > And all request will use this global Connection
> > variable to query the database. Certainly I ensure the only a request
> can
> > aceess the variable at the same time.
> > I test the servlet using the servletrunner. There are no
> > problem in all cases.
> > But when I use the servlet in the javawebserver2.0(trial version) and
> connect the oracle
> > database, I found a problem:
> > first query has no problem, but later query will hang forever (do
> not
> > return).
> >
> > The problem do not happen when connecting other database. If using the
> > servletrunner to test this servlet, it can connect to all database
> including the oracle database too.
> >
> > My oracle version is 7.3.3 in the WindowsNT.
> >
> > Following is my code segment:
> >
> > public class MapdPHServlet extends HttpServlet
> > {
> > Connection connection ;
> >
> > public MapdPHServlet()
> > {
> > super () ;
> > try
> > {
> > String URL=new String("jdbc:odbc:testdb");
> > Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
> > connection = DriverManager.getConnection(URL);
> > }
> > catch (Exception e) {System.out.println ("# Initialize Error : " +
> > e.toString()) ;} ;
> > }
> >
> > public void init (ServletConfig config) throws ServletException
> > {
> > super.init (config) ;
> > System.out.println (" # Initalize MapdPH Servlet...") ;
> > }
> >
> > public void destroy()
> > {
> > super.destroy();
> > try
> > {
> > connection.close();
> > }
> > catch (Exception e) {System.out.println ("# Destroy MapdPH Servlet
> > Eorror") ;} ;
> > System.out.println (" # Destory...") ;
> > }
> >
> > /************* doPost() ***********************/
> >
> > protected void doPost (HttpServletRequest req,
> > HttpServletResponse res)
> > throws ServletException,IOException
> > {
> > // do a simple query and return the result to the client
> > // I ensure there are only a request at the same time
> > try {
> >
> > Statement statement=connection.createStatement();
> > String SQLStatement = "Select * from person";
> > if( statement.execute(SQLStatement) )
> > { //send the result to the client
> > .....
> > }
> > else // with Result Set
> > {
> > }
> >
> > statement.close();
> > }
> > catch (Exception e)
> > {
> > System.out.println (e) ;
> > }
> >
> > } // end of doPost()
> >
> > Do you think it is my problem or the javawebserver's problem? Can you
> give
> > me some
> > suggestion to deal with the problem? At present, I build the connection
> in
> > the doPost and
> > close the connection before exit the doPost in order to solve this
> problem.
> >
> > By the way, there are some parameters in the javawebserver:
> > Service Tuning ----- General ------------ Capacity
> > --- Handler Threads
> > --- Connection Persistence
> > I found the javawebserver often hang when there are two many users(about
> 50)
> > accessing the server simultaneously if I use the default value of these
> parameters.
> > Even if I maximize all parameters, the javawebserver still hang
> occasionally.
> > Do you think it is my problem or the javawebserver's problem?
> >
> > thanks in advance,
> >
> > jianjiang zeng
> >
> > ________________________
> > Are you ChinaRen?
> > �"Y�-中�>�人�s"�"�子�"Y活
> > http://www.chinaren.com
> >
> >
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