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From "Pradeep Chauhan" <>
Subject RE: Win2kSP4, Apache-2.0.49 + Tomcat-5.0.27 + mod_jk2-2.0.43 - Memory Reference Error
Date Mon, 26 Jul 2004 12:50:00 GMT

I faced the same issue when concurent user are more.
In this case we need to Increase the JDK heap size.
On windows we can install the Tomcat in 2 ways

1. As a NT service
2. Command prompt

In 1 Case u need to add 2 additional parameters in registry.
"JVM Option Count"=5
"JVM Option Number 3"="-xms512m"
"JVM Option Number 4"="-xmx512m"

The Minimum and Maximum size of HDK heap size  should be 1/3rd of Total RAM,
as these OS need big memory for their own purpose.

In 2nd Case Increase the JDk size with editing JAVA_OPTS variable in
Catilina file.

I hope your problem will get solved.

With regards,
Pradeep Chauhan

-----Original Message-----
From: Noah []
Sent: 26.07.2004 18:14
Subject: RE: Win2kSP4, Apache-2.0.49 + Tomcat-5.0.27 + mod_jk2-2.0.43 -
Memory Reference Error

No luck with eliminating the error so far (increasing JVM memory and
the configuration changes I've tried didn't work). Any more ideas?


Old message:
Thanks, I've set those options and it at least hasn't broken anything... I
be able to tell if it has helped until normal traffic resumes on Monday

I'm not sure I can give a step by step explanation of what we did to setup
the connection... it involved a lot reconfiguring, finding information about
errors and what caused them, and finding the workarounds. Maybe you
could start a new thread with some information from your logs and configs,
I may be able to recognize some problems that we ran into. I'll give a basic
account of what we have done anyway, as best as my memory serves, in
case something might help you:

- We already had Apache and Tomcat installed, it had been forwarding
  using mod_proxy.
- Uncommented the correct connector in server.xml. Later we changed
  the default options to be what currently appears (you can view this
  in the original message). Still using the default port (8009).
- Configured mod_jk2 settings in httpd.conf. Originally we were setting
  all configuration of jk2 there. Now, we have moved all configuration
  into At the time that I sent the mail, we were
  setting URI info in httpd.conf. I have now also moved that into Additionally, I have changed the configuration
  so that URI's are mapped to the load balancing group instead of
  directly to a worker, and the worker is mapped to the load balancer.
  I'll paste the relevant section in below.
- Configured, as described above and included in
  the original post. The status worker is really useful for looking at
  your configuration to try to find problems, by the way.
- Note, we have made no changes in It is effectively
  empty, thus using all of the default settings.

I can't think of anything else. I'll post a followup on Monday if either of
the changes (increasing memory and reconfiguring to use the lb: group)
end up causing some difference in behavior.

- Noah

Updated Config:


<IfDefine SSL>

      <Directory />
          Options FollowSymLinks
          AllowOverride none

      SSLEngine on
      SSLCertificateFile conf/ssl.crt/entrustexampleserver.crt
      SSLCertificateChainFile conf/ssl.crt/entrustchaincert.crt
      SSLCertificateKeyFile conf/ssl.key/example_server_com.key

      <IfModule mod_jk2.c>
          <Location "/jkstatus">
              Order Deny,Allow
              Deny from all
              Allow from
          <Location "/app/*">
              Redirect permanent /app/login.jsp






>I did a search on google and this is what I found...
>open catalina.bat or the equivalent file.
>set JAVA_OPTS to the desired value.
>ex: set JAVA_OPTS=-Xms128 -Xmx128
>htp  (Hope This Helps)
>>-----Original Message-----
>>From: Tonte Pouncil
>>Sent: Friday, July 23, 2004 9:59 AM

>>You may want to try increasing the jvm memory heap for Apache and/or
>>Tomcat.  I have experienced out of memory error with Tomcat before.
>>I fixed the issue by increasing the jvm memory heap.  I forget the
>>command that I used and I am no longer working at the company I
>>configured Tomcat to use more memory, but if you do a search on
>>google you should be able to find some kind of documentation.
>>I have the same set up you have, but I have been unable to get
Apache to >>forward jsp request to Tomcat.  Can you provide me with a
step by step >>instructions as to what you did?
>>>-----Original Message-----
>>>From: Noah []
>>>Sent: Friday, July 23, 2004 9:24 AM

>>>OS: Windows 2000, Service Pack 4
>>>Apache ver:  2.0.49
>>>Tomcat ver:  5.0.27
>>>mod_jk2 ver: 2.0.43
>>>We have a server set up to forward requests through Apache to Tomcat
>>>mod_jk2. The setup works, except that periodically it will throw an error
>>>follows on the server:
>>>  Application popup: Apache.exe - Application Error : The instruction at
>>>  "0x6eec7826" referenced memory at "0x00000000". The memory could not
>>>  be "read".
>>>On the user end, the web app is not interrupted when this happens.
>>>In the mod_jk2 error log, the following lines appear when this error
>>>  [Wed Jul 21 10:07:21 2004] (error ) [jk_worker_ajp13.c (546)]
ajp13.service() ajpGetReply recoverable error 3
>>>  [Wed Jul 21 10:07:21 2004] (error ) [jk_worker_ajp13.c (546)]
ajp13.service() ajpGetReply recoverable error 3
>>>  [Wed Jul 21 10:07:21 2004] (error ) [jk_worker_ajp13.c (648)]
ajp13.service() Error  forwarding ajp13:localhost:8009 1 0
>>>  [Wed Jul 21 10:07:21 2004] (error ) [mod_jk2.c (752)]
mod_jk2.handler() Error connecting to tomcat 3, status 200

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