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From (Steve Quail)
Subject Re[2]: Using Apache/Tomcat in high-traffic site
Date Mon, 19 Mar 2001 11:36:15 GMT
     I'm just putting together a prototype on the Internet using Tomcat, 
     we've got two Linux boxes and load is spread over the two hosts using 
     a BigIP load-balancer. The mod_jk config is ok when you understand 
     whats going on, local and remote Tomcat instances aren't specially 
     distinguished apart from having a different IP address. mod_jk handles 
     the sticky session part so going in on different web servers each time 
     is fine. 
     mod_jk could do with better documentation in this regard and its very 
     easy to configure it so that it does absolutely nothing and logs no 
     errors whatsoever ! Direct all contexts to the load balancer worker 
     not the ajp13 workers and have the load balancer worker spread things 
     I'm interested in your experience of heap sizes, in my prototype I've 
     ignored it, how would I know if I'm near - do you have a feel for how 
     much memory you need per session (assuming application doesn't store 
     much data in the session).

______________________________ Reply Separator _________________________________
Subject: RE: Using Apache/Tomcat in high-traffic site
Author:  Tim Sullivan <> at Internet-po
Date:    16/03/01 11:24

Hello Gavin,
I am considering doing the same thing on almost the same hardware (e4500 + 
Did you end up finding any performance examples or otherwise for this?  If 
so, could you forward it my way?
Thanks in advance,
 -----Original Message-----
From: []
Sent:   Wednesday, March 14, 2001 12:55 PM 
Subject:        Using Apache/Tomcat in high-traffic site
I am looking to use Apache and Tomcat in my company's production web site. 
Before I can convince management that this is a good idea I need some 
information so I am confident.  If anyone can help I'll be very grateful.
First of all I'll give you a picture of the overall architecture that I want 
1)  For fault-tolerance and scaleability we want to have several instances 
Apache running over a number of machines.  These will be load balanced by a 
of Cisco Local Director boxes, because we already own a couple of them. 
>From a
brief look through the operating manual on Cisco's web site I get the 
that Local Director cannot support "sticky" load-balancing.  Please correct 
if I'm wrong.
2)  We will run several instances of Tomcat (version 3.2.1 most likely) on 
back-end servers.  These are a couple of Sun E10000s with 32 processors 
These are partitioned up into domains, so that we end up with 12 processors 
each machine dedicated to running Tomcat.  Each domain has 2GB of RAM. 
are other domains dedicated to databases, etc...
3)  Each instance of Apache will be using mod_jk in a "sticky" load-balanced 
configuration.  Every instance of Apache (and so mod_jk) will have workers 
defined for every instance of Tomcat on both E10000s.  In other words, a 
instance may receive a request from any instance of Apache.
The things I need to know :)
1)  Each request to our site will be assigned seemingly at random to one of 
Apache instances by the Cisco boxes.  Can the "sticky" part of mod_jk cope 
this?  i.e.  Will mod_jk pass the request to the correct Tomcat instance 
though it does not share context information with the other Apache 
2)  What is the best way of running Tomcat on the large E10000s?  Should I 
just a few very large processes (say 2 x 800MB max heap) for Tomcat or 
should I
run many smaller processes (say 16 x 100MB max heap)?  Has anyone got any 
experience with making Tomcat (or any Java based server) scale to machines 
this size and power?  I want to get good performance, but I don't want to 
compromise stability.
3)  Has anyone used Tomcat in a mission critical environment?  I use it in 
development all the time and I'm very happy with it, but I'd like to get 
impression of how it holds up.
4)  Are there any security considerations with this configuration?  We have 
firewalls, intrusion detection kit, etc... for which we have a dedicated 
maintenance team.  I'm really only interested in the software here.  Has 
used the new Java 2 security features with Tomcat?
Thank you very much indeed!
Cheerio, Woody.
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