Re: [JDBC] Getting "This ResultSet is closed" exceptions

On Monday 18 February 2008 14:48:24 Paul Tomblin wrote:
> Forgive a possibly stupid question, but how would a class know whether
> there is a Connection for this thread already?  I use a simple static
> to hold the Connection, and so I get one for the whole program.

That sounds like a bad plan to me. You're going to interleave transactions etc. (You are using transactions, aren't you? :) Look into connection pools (apache has DBCP http://commons.apache.org/dbcp which is good), or otherwise use a threadlocal that keeps a connection per thread around.

> But
> there is a lot of asynchronous stuff going on with GUI callbacks,
> external "messages" and RMI calls, etc.  Do I have to create and
> destroy a connection in every callback, or use some sort of thread
> pooling system?  A previous engineer on this project had one subsystem
> that was creating a new database connection every second, and then
> closing it a few milliseconds later - that seems like madness to me

Creative, but not very scalable :)

jan

-- 
--------------------------------------------------------------
Jan de Visser                     jdevisser@digitalfairway.com

                Baruk Khazad! Khazad ai-menu!
--------------------------------------------------------------

---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
       choose an index scan if your joining column's datatypes do not
       match