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From Antonio Fiol Bonnín <>
Subject Re: When is Tomcat 5 Release version scheduled to come out?
Date Sat, 22 Nov 2003 10:13:13 GMT


I'll begin from the end...

I did not present evidence, that is true, but I explained the symptoms. 
I tested three configurations:

1 Apache + 1 Tomcat;    1 Apache + 2 Tomcat;    1 Apache + 3 Tomcat

All three gave me very similar performance results. Measurement tool was 
"JMeter". Difficult pages were generated faster using three tomcats than 
using one tomcat, and trivial pages were faster with one tomcat.

Probably all this is due to the overhead of replicating the sessions, 
but I am not sure.

We also used Apache AB to test it. We did it against one nearly static 
JSP page. With low concurrency levels (less than 5), 2 tomcats give more 
throughput than one. With higher concurency levels (5 or more), 2 
tomcats give worse throughput.

Probably, again, I think, because of the overhead of creating hundreds 
of sessions and replicating them. But, again, I am not sure.

So, coming back to the beginning...

I expect people to say:

- "Hi! I am using it for reliability, but you are right and we see no 
increase on performance here" (experience - bad)
- "Hello, we found that if you change parameter "foo" to have value 
"bar", you will get a huge increase on performance" (facts)
- "Dear Antonio, use sticky sessions for better performance" (advice)
- "Antonio, your test tool is crap. Use "foobarMatic" to test. Our tests 
gave results X, Y, and Z." (opinion and facts)
- "Hi! We use session replication and get huge performance increase. I 
can't see why you don't. Here is my server.xml so you can compare it to 
yours." (experience - good)

You see, I am open to a variety of kinds of comments. Of course "It is 
great, use it..." will not help a lot without "... use it this way 
better than that", but if someone says "It is great", I will probably 
send him private e-mail, and when/if we reach a good conclusion on why 
facts are different, I promise I will post our conclusion here so that 
it can be documented.

Thank you for your interest!

Antonio Fiol

Shapira, Yoav wrote:

>Umm, what are you looking for people to say?  "It's great, use it" doesn't help you. 
Yet you don't present any evidence that it's not great.  What are you experiencing, and why?
>Yoav Shapira
>Millennium ChemInformatics
>>-----Original Message-----
>>From: Antonio Fiol Bonnín []
>>Sent: Friday, November 21, 2003 3:42 PM
>>To: Tomcat Users List
>>Subject: Re: When is Tomcat 5 Release version scheduled to come out?
>>I am a bit deceived about Tomcat (5) clustering with session
>>replication, and our company is considering (against) its (upcoming)
>>usage on production systems for high-load environments.
>>Expectancies were that it would increase reliability AND performance.
>>Preliminary home-made tests are showing increased reliability(*) but NOT
>>substantially increased performance (somewhere around 80%-120% depending
>>on the difficulty of generating the pages). Maybe it's application-
>>Any comments, opinions, facts, or advice, as well as any related
>>experiences (good or bad) will be greatly appreciated.
>>Personally, I would love to see it in production, but I will only push
>>it forward if I am convinced of its advantages. At the moment, I need
>>more evidence before making a decision.
>>Thank you very much.
>>Antonio Fiol
>>(*) No sessions lost on crashes.
>>Filip Hanik wrote:
>>>you can use T4 with
>>>----- Original Message -----
>>>From: <>
>>>To: "Tomcat Users List" <>
>>>Sent: Friday, November 21, 2003 11:07 AM
>>>Subject: Re: When is Tomcat 5 Release version scheduled to come out?
>>>Is it a good idea to use Tomcat 5 beta for develop and production if we
>>>wanted the clustering capabilities?

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