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From "Dwight Powell" <>
Subject Upgrade to Tomcat DECREASES Performance?
Date Mon, 30 Jul 2001 17:09:06 GMT
OK, let's see how good you folks are:

I work for a large national not-for profit membership organization.  We've
got a large database application that we serve to our members from a small
group of servers out of our national office.  About a week ago, we upgraded
our servers, moving from Apache JServ/mod_jserv/AJP12 to
Tomcat/mod_jk/AJP13.  Ever since the upgrade, our servers have been HIGHLY
unstable (our 3 busiest servers have each crashed at least once a day for
the last week)  and we're HIGHLY confused.  The only real change has been
the move to Tomcat, which we thought was a large upgrade, but our app has
been acting as if we downgraded!

Before the upgrade, application was having some performance issues (record
locking, result set not found errors), probably caused by the large load on
our servers combined with some inefficiencies in the code.  After the
upgrade, the same performance errors exist, but seem to be magnified, as if
Tomcat is working SLOWER than JServ.  But here's the worst part:

At least once a day (usually after running for a while), the application
will simply stop responding - users will attempt to save forms and/or
navigate between pages and will never get a respond (eventually they'll get
a "Page Cannot Be Displayed Error").  When the server is in this state, we
check the running processes and we see lots of java threads loaded and
waiting for response, but none of them is RUNNING, so I don't THINK this is
a runaway thread problem.  Once the server hangs like this, our processor
usage by the JVM will go down to 0% and stay there until we restart Apache
and Tomcat.

Here's our specs:

SERVER SPECS (average):

Dual Pentiums (1 Ghz)
2.5 GB RAM
Red Hat Linux 7.1

Apache 1.3.14
Apache JServ (with mod_jserv and ajp12)
IBM JDK 1.3-5
Cloudscape 3.5

Apache 1.3.14
Jakarta Tomcat 3.2.2 (with mod_jk and ajp13)
IBM JDK 1.3-9
Cloudscape 3.5

So... does anyone out there have any idea why we're seeing these problems?
Where should we focus our investigation?   Should we just go back to JServ,
or is Tomcat REALLY better?

Thanks to one and all...

Dwight Powell
Manager of Systems / Lead Programmer

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