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Date: Tue, 29 Jul 2003 13:37:03 +0100
From: Paul Thomas <paul@tmsl.demon.co.uk>
To: Achilleus Mantzios <achill@matrix.gatewaynet.com>
Cc: LEON <ldai@accunettech.com>,
	"pgsql-sql @ postgresql . org" <pgsql-sql@postgresql.org>
Subject: Re: How can I to solute this problem?
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	<Pine.LNX.4.44.0307291409400.27224-100000@matrix.gatewaynet.com>
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	from achill@matrix.gatewaynet.com on Tue, Jul 29, 2003 at
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On 29/07/2003 17:09 Achilleus Mantzios wrote:
> 
> You may take a look at jboss connection pool
> mechanism. (postgresql.xml)

He doesn't mention JBoss, just Tomcat so I don't believe the 
postgresql.xml will help him much. He could use Tomcat's built-in 
connection pooling 
(http://jakarta.apache.org/tomcat/tomcat-4.1-doc/jndi-datasource-examples-howto.html) 
but should note that there is an error in the web.xml fragment: 
<res-ref-name>jdbc/mydb</res-ref-name> should be 
<res-ref-name>jdbc/postgres</res-ref-name>. Leon, if you need more help 
please feel free to contact me off-list.

> 
> Also a good way of ensuring that your app will
> not leave open stale postgresql connections
> is to initially configure your pool to only have a small
> number of connections (e.g. 2,3).

Good advice for any form of connection pooling.

> 
> If your J2EE components (e.g. jsps) are fast enough
> you should start facing connection shortages
> only after the load on your machine increases
> significantly. (and then safely increase the maximum
> number of connections in your configuration (both postgresql wise
> and app server (conn pool) wise).
> 
> 
> On Tue, 29 Jul 2003, Paul Thomas wrote:
> 
> >
> > On 29/07/2003 07:18 LEON wrote:
> > > I use tomcat+linux_postgresql+jsp to develop system.
> > >
> > > I start postgresql with 1024 processes.
> > > FE:
> > > postmaster -i -S -N 1024 -B 2048 -D /var/lib/pgsql/data
> > >
> > > My jsp doesn't implement connection pool.It directly connects
> postgresql
> > > by jdbc.
> >
> > IME, that is not a good way to do it. Use a connection pool.
> >
> > > After I run the Ui some times, the UI(jsp) would report "ieSorry,too
> many
> > > clientslg" .The exception is SQLException.
> > >
> > > I must restart tomcat or postgresql I can continue to running my UI.
> >
> > My guess would be that you have a bug in your application which is not
> > always closing the connection so eventually you exceed max_connections.
> 
> > You should always close the connection in a finally{} block so that is
> > guaranteed that it will be closed regardless of any earlier exceptions
> > which are thrown.
> >
> > HTH
> >
> >
> 
> --
> ==================================================================
> Achilleus Mantzios
> S/W Engineer
> IT dept
> Dynacom Tankers Mngmt
> Nikis 4, Glyfada
> Athens 16610
> Greece
> tel:    +30-210-8981112
> fax:    +30-210-8981877
> email:  achill at matrix dot gatewaynet dot com
>         mantzios at softlab dot ece dot ntua dot gr
> 
> 
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