Re: Servlet problems

Nikola-

I have a thought which doesn't match your description precisely, but might
still be worth a try if you haven't already thought of it. I'm reminded of
it because I had a similar mystery once where my jsp would die mysteriously
unless I interrupted it before completion with a debug statement.

In my case the problem was that totmcat starts you off with a fairly small
chunk of memory to write each page to. I don't remember the exact number,
but I'm thinking it was 8K or 16K. The problem was that I overran this
buffer, resulting in an error that was misleading every time the page grew
to a certain size. A sizable email directory might be big enough to do this.

The fix was to insert this line at the top:

<%@ page buffer="64kb" %>

If this doesn't help, I'd suggest looking in Tomcat's work directory for the
java code that gets produced & posting a copy of it to the list. Although
many folks on the list don't speak jsp, they'll all be able to grok the java
version.

-Nick

> -----Original Message-----
> From: pgsql-jdbc-owner(at)postgresql(dot)org
> [mailto:pgsql-jdbc-owner(at)postgresql(dot)org]On Behalf Of Nikola Milutinovic
> Sent: Monday, December 17, 2001 9:32 AM
> To: PostgreSQL JDBC
> Subject: [JDBC] Servlet problems
>
>
> Hi all.
>
> I'm a bit confused here. I'm using Tomcat JSP/Servlet engine. I
> have a database in PostgreSQL, which holds a table describing an
> n-tree structure (hierarchy). I would like my JSP page to able to
> display (if parameter "print" is present) a complete sub-tree of
> a given node. This is a simple recursion. What I'm trying to do
> is make our coroporate E-Mail address book, so I have
> organizational units and users.
>
> Without recursion everything works fine, all the direct subnodes
> are displayed. When I use recusrion to include all subnodes, I
> get strange errors.
>
> First, it was killing the response in the middile of a table, in
> the middle of a row. Now it dies with "NullPointerException:
> next()". In other words, in one of the "ResultSet.next()"
> methods, it runs into a non existant ResultSet.
>
> I have tried putting a "breakpoint" (throwing a ServletException)
> on all lines of my JSP page. When there is a "breakpoint" I do
> not run into a NullPointerException. When I remove it, I have exception.
>
> My conclusion was that I get the error AFTER my JSP page starts
> emerging from the recursion (if it was inside recursion, it would
> have been stopped by the "breakpoint"). So, after a page calls
> itself once, the "insider" does it's thing and then exits and
> releases control to it's caller, the the exception occurs.
>
> I must admit that JSP page closes it's JDBC objects, I thought it
> would be OK, since the page creates them.
>
> This is the flow of events:
>
> OUDisplay.jsp [instance 1]:
> ----------------------------
> DriverManager.getConnection()
> Connection.createStatement()
> Statement.executeQuery()
> while( ResultSet.next() ) {
> ...
> <jsp.include page="OUDisplay.jsp" />
>
> OUDisplay.jsp [instance 2]:
> ----------------------------
> DriverManager.getConnection()
> Connection.createStatement()
> Statement.executeQuery()
> while( ResultSet.next() ) {
> ...
> }
> ResultSet.close()
> Statement.close()
> Connection.close()
> --------------[instance 2]-
>
> }
> ResultSet.close()
> Statement.close()
> Connection.close()
> --------------[instance 1]-
>
> The problem occurs inside the outer "next() {...}", which leads
> me to believe that Some objects in the "instance 1" get screwed
> up, but I don't know how.
>
> Any insight?
>
> Nix.
>
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