Upgrade to Tomcat DECREASES Performance?

[Dwight Powell <dp...@naccrra.org>]

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

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

NEW CONFIGURATION:
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
NACCRRA (www.naccrra.org)
dpowell@naccrra.org

Re: Upgrade to Tomcat DECREASES Performance?

[Jeff Kilbride <je...@kilbride.com>]

Good enough to have answered this question several times. Have you checked
the archives?

http://mikal.org/interests/java/tomcat/archive/view?mesg=35371
http://mikal.org/interests/java/tomcat/archive/view?mesg=33145
http://mikal.org/interests/java/tomcat/archive/view?mesg=30821
http://mikal.org/interests/java/tomcat/archive/view?mesg=26859

Other things I would suggest:

-- If you're using ajp13, you can tune down the number of threads for your
ajp12 connector

-- Use the mod_jk module that comes with TC 3.3. It allows you to stop and
start TC without restarting Apache. You can download the 3.3 distribution
and make it yourself, or just use the pre-compiled binary for Linux (which
is what I use). It's compatible with 3.2.x and can be found here:

http://jakarta.apache.org/builds/jakarta-tomcat/release/v3.3-b1/bin/linux/i3
86/

-- Upgrade to 3.2.3. It's really easy. You just copy the jar files into your
existing installation. The release notes explain it.

-- Monitor the tomcat-dev list. You learn a lot more there than you do on
the user list (even though you don't normally post there...)

Thanks,
--jeff

----- Original Message -----
From: "Dwight Powell" <dp...@naccrra.org>
To: "Tomcat Users" <to...@jakarta.apache.org>
Sent: Monday, July 30, 2001 10:09 AM
Subject: Upgrade to Tomcat DECREASES Performance?


> 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
>
> OLD CONFIGURATION:
> Apache 1.3.14
> Apache JServ (with mod_jserv and ajp12)
> IBM JDK 1.3-5
> Cloudscape 3.5
>
> NEW CONFIGURATION:
> 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
> NACCRRA (www.naccrra.org)
> dpowell@naccrra.org
>
>