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From "Mark Gastel" <>
Subject RE: Hardware loadbalancing with JK2
Date Tue, 12 Aug 2003 01:45:58 GMT
Hi Eric,

Thanks.  At this point I'm a bit more comfortable using a hardware
loadbalancer over the jk2 stuff.  we've been using a css in production for
well over a year.  Unlike tomcat or apache I've seen very little movement in
the jk2 code base and the documentation is very confusing at times.

My problem is not the basic configuration ...I have a working setup.  My
problem is because mod_jk2 is using a connection cache (keepalive
connections or something) it is sending requests to a service that has been
disabled.  This really sucks if you want to upgrade a tomcat instance.  If I
can get jk2 to establish a new connection with every request this problem
disappears.  No matter what I do I can't get this to happen.


-----Original Message-----
From: Eric J. Pinnell []
Sent: Monday, August 11, 2003 5:04 PM
To: Tomcat Users List
Subject: Re: Hardware loadbalancing with JK2


Using the CSS between Apache and Tomcat seems a bit overkill as Tomcat
provides all the functionality that a CSS would.  However I think you can
get it to work.  All you need is a single worker to the CSS.  From there
the CSS should bust it out and spread it across the various Tomcats.
There wouldn't be any loadbalancing in the JK2 configuration.

Just like a web server might have multiple hosts behind it, to the outside
world you only see one IP.  Same thing goes for JK2.

I don't have a properties file handy but search the archives and you'll
find an example.  You just want a real basic single worker config.  I
think there might be one in the JK2 docs.

Make sure to configure the CSS to make the sessions sticky by some
mechanism (unless you are using clustering) otherwise Tomcat could goof


On Mon, 11 Aug 2003, Mark Gastel wrote:

> Hi,
> I am trying to get hardware load balancing to work between apache
> 2.0.46/mod_jk2, a cisco css and tomcat 4.1.27.  The way this works is an
> ajp13 service has been created on the css.  Apache talks to this css ajp
> service which is split among several tomcat instances...  Now the problem:
> Because mod_jk2 seems to have some form of connection caching going,  when
> disable a tomcat instance it still receives ajp13 connections.  Is there a
> way to disable the connection caching in JK2 and forcing it to establish a
> new connection with every hit?  I know this would give a performance hit,
> but it will give me fine grain control over how traffic is distributed.
> If you could attach a piece of a file I would really
> appreciate it!!
> Thanks
> Mark

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