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From André Warnier ...@ice-sa.com>
Subject Re: pick load
Date Thu, 26 Aug 2010 08:21:44 GMT
Alexandre Chapellon wrote:
> Hello,
> 
> I'm quite new to tomcat and have an old webapps running on tomcat 4.1
> and jvm 1.4.2 with apach2.2 in front ofthem (using modjk).
> I'm trying to get ready for a comming pick load I will have to face.
> I Try to do some benchmark using ab and the jkstatus worker.
> Whatever the configuration of my connecter (both on the apache or tomcat
> side) I never go upper than 20 requests / second.
> Here are few  parameters I changed in order to get better performances:
> 
...
Hi.
It is very likely that by changing the default parameters of Apache, mod_jk and Tomcat 
without first knowing exactly where the "slowness" is happening, you are making the 
situation worse rather than better.

It is also very likely that the webapp itself is the limiting factor.

Apache + mod_jk + Tomcat, in their default configuration, by themselves, can handle 
several hundred requests per second.  If you do not believe this, then try it yourself : 
set up a static html page inside tomcat's ROOT webapp, make sure that the mod_jk 
configuration forwards these requests to Tomcat, and then use ab to make requests to that

static page, just to convince yourself.
Then use one of the Tomcat standard example webapps, and do the same.

Then, use Tomcat's AccessLogValve 
(http://tomcat.apache.org/tomcat-6.0-doc/config/valve.html#Access_Log_Valve) to compare 
the processing times between static pages, an example webapp and your webapp.

When you really understand where the problem seems to happen, then come back and ask more

precise questions.

The point is : the default configuration of Apache, mod_jk and Tomcat is *already* tuned 
to perform well in most standard situations. If there existed any way "in general" to tune

these things better, and the Apache, mod_jk and Tomcat developers knew it, then of course

*that* would become the default configuration.

The point is also : nobody here has any idea of what your old webapp is doing; only you 
know that. If it is making 10,000 disk accesses each time it processes a request, then 
maybe what you need is a faster disk. If it builds a huge table in memory each time it is

called, then maybe you need more memory. Etc..

One last thing : Tomcat 4.1 and the JVM 1.4.2, both, are about 10 years old, and not 
supported anymore.  The current versions are free, and supported.  Do yourself (and 
everyone else) a favor and make your testing on the latest versions.  Your webapp should 
work just as well (or better) with them.

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