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From "Wagoner, Mark" <>
Subject RE: Tomcat Scalability - Long
Date Thu, 24 Oct 2002 19:43:52 GMT
We have a similar hardware setup (PIII 1GHz 512M) but running Tomcat 4.0.4
on Win2k/IIS and accessing a DB2 database on a separate iSeries server.

The system is used by our sales reps in the US and Canada (about 30) over a
VPN, so it can see activity at any time.  It never really gets hammered but
traffic seems to come in spurts with the highest load I have seen of about 5
simultaneous users and the longest "session" (although we don't use session
objects) of about 45 minutes.  Keep in mind that I have never actually
monitored the traffic, just made mental notes as I was reviewing the log

So far the only time we have had to restart the machine is to install
another MS security patch.  The longest continual uptime has been a little
over 19 days (the server has only been in production about 10 weeks) and the
memory used by Tomcat seems to hover right around 24M.  Response time is
always in the sub second range, except for a few database queries that seem
to take a little longer (still need to do some SQL tuning).

I don't know if you can call this "solid" information, but so far I have not
seen anything to worry about scalability wise.

-----Original Message-----
From: Brandon Cruz []
Sent: Thursday, October 24, 2002 3:36 PM
To: Tomcat Users List
Subject: Tomcat Scalability - Long

Does anyone have any solid information about the scalability of Tomcat?  It
seems very limiting to me, but that is hopefully due to improper
configuration.  Here is our situation and what seems to be happening under a
small amount of stress.

---About our Environment---

PIII 1.0Ghz
512 Meg Ram
Linux RedHat 7.1
MySQL Database
Apache 1.3.x
mod_jk - logging turned all the way down
Tomcat 3.2.4 - contexts *are* reloadable right now
SUN JDK 1.3.1_01

---About our Application---

Our Application is a content management tool that reads and writes to the
MySQL Database and reads and writes files.  All the pages within this
application are served by Tomcat 3.2.4.  About 80-120 people per day log
into this application and spend anywhere from 10 minutes to one hour working
on the application.  At any given time there are between 15 and 50 active
database connections.

---What we are seeing---

Tomcat needs to be restarted every few days.  If we don't restart it, it
seems tomcat eventually locks up and does not respond at all.  No errors or
anything are reported, it just will not respond.  Apache continues to work
during this time and all static HTML pages are accessible.

CPU - The processor usage seems to slowly increase as time goes on.  After
about one day, it seems one java process uses 30% of available CPU or more,
depending on whether users are performing operations or not.  When nobody is
doing anything, the processer still seems to be sitting around 30% until
tomcat is restarted.  This seems to cap after three to five days and not
increase too much more.

RAM - This slowly increases and never stops increasing.  We do not have any
special parameters set for the VM when it starts, but this does not seem to
matter.  The RAM gets up to about 135 MB after four or five days, but would
continue to grow if tomcat were not allowed.

Can anyone explain this behavior, talk about the scalability of Tomcat, or
provide any similar working solutions that perform better than this?  Is it
normal, should we just throw more hardware at it?  Are there configuration
parameters that can be used to increase performance, such as set
reloadable=false in all contexts?  Would we get better performance if we
upgraded to 4.x, or would that just be more work for little improvement?

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