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From <Carlos.Fernan...@usitc.gov>
Subject RE: mod_jk Random Errors
Date Fri, 28 Oct 2005 16:35:57 GMT
Rainer,

 

I am a colleague of Jacks.  Thank you for all of your suggestions.

 

FIREWALL

 

>  Since that error number was shown in the log line, I assume that a
system

>call returned this error. Is it possible, that your network is
unstable? 

 

>Maybe you should involve your network people.

 

We have since pulled in the admin responsible for the apache and tomcat
servers.  He informed us that both machines had active software
firewalls.  We have since deactivated both software firewalls.

 

This degradation normally manifests itself within 60 minutes of
restarting apache.  We are now at 2 hours and apache is running well.

 

We ran across a post on redhat that seems to describe our problem
exactly -
https://www.redhat.com/archives/fedora-list/2005-March/msg06447.html.

 

Other than the AJP port specifically mentioned in the workers.properties
and the tomcat server.xml files (8009), is another port used?  Does
mod_jk have a required control port?

 

OTHER ISSUES

 

Assuming that the firewall was not the problem, we are working along a
few other lines.

 

> Also check stability of name

>service, because you used a name and not an IP in workers.properties
(that

>should only be relevant when establishing new connections).

 

This does not seem to be the issue.  When mod_jk logs the error, it
notes the remote hosts IP address in the error message.  This seems to
suggest that naming services are not an issue.

 

[Fri Oct 28 10:06:24 2005] [error]
ajp_connection_tcp_get_message::jk_ajp_common.c (961): Can't receive the
response message from tomcat, network problems or tomcat is down
(192.168.4.17:8009), err=-113

 

> What's missing is information about your apache process/thread
>configuration (that's what is meant with MPM). This info usually is
>located close to the beginning of httpd.conf.

 

I checked the settings apache was compiled with and it stated:

 

-D APACHE_MPM_DIR="server/mpm/prefork"

 

The conf file has the following settings for prefork:

 

<IfModule prefork.c>

StartServers       8

MinSpareServers    5

MaxSpareServers   20

ServerLimit      256

MaxClients       256

MaxRequestsPerChild  4000

</IfModule>

 

Our workers.properties file is set as follows:

 

worker.list=ajp13

worker.ajp13.port=8009

worker.ajp13.host=eofapps.usitc.gov

worker.ajp13.type=ajp13

worker.ajp13.cachesize=10

worker.ajp13.cache_timeout=600

worker.ajp13.socket_timeout=300

 

Based on the fact that we are running prefork, we know we need to reduce
the cachesize down to 1.  However, we don't want to modify the file
until we can isolate the impact of removing the software firewall.

 

Thank you for all of your help.

 

Carlos

 

-----Original Message-----
From: jack rodriguez [mailto:tomcatlist@gmail.com] 
Sent: Wednesday, October 26, 2005 3:13 PM
To: Fernandez, Carlos
Subject: Fwd: ~ mod_jk Random Errors

 



---------- Forwarded message ----------
From: Rainer Jung <tomcat-user@kippdata.de>
Date: Oct 21, 2005 4:25 PM 
Subject: Re: ~ mod_jk Random Errors
To: Tomcat Users List <users@tomcat.apache.org>

>> Which version of mod_jk are you using?
>
>   1.2.14 Current Version

OK

> What is errno 113 on your platform?
>
>  Linux Error :113 No route to host

Since that error number was shown in the log line, I assume that a
system
call returned this error. Is it possible, that your network is unstable?


Maybe you should involve your network people. Also check stability of
name
service, because you used a name and not an IP in workers.properties
(that
should only be relevant when establishing new connections). 

> Each tcp connection from apache to tomcat blocks a thread inside
tomcats
>> jk connector thread pool, that exclusively services requests coming
over
>> that connection. So what are your MPM settings inside apache
httpd.conf,
>> your workers.properties settings and your ajp 13 connectors settings
in
>> server.xml?

>  httpd.conf
>  ####################
> # SETUP FOR TOMCAT #
> #################### 
...

What's missing is information about your apache process/thread
configuration (that's what is meant with MPM). This info usually is
located close to the beginning of httpd.conf.

>
>  Workers.properties 
>  worker.list=ajp13
> worker.ajp13.port=8009
> worker.ajp13.host=eofapps.usitc.gov
> worker.ajp13.type=ajp13

If you use apache 2 then you should also set

worker.ajp13.connection_pool_size=NUMBER_OF_THREADS_PER_PROCESS 

where NUMBER_OF_THREADS_PER_PROCESS is the number of threads per process
configured in your apache mpm (=1 for prefork, but usually much bigger
than one for worker)

You should also read documentation about the following possible
attributes 
(I include their default values):

- cache_timeout (0)
- socket_timeout (-1 = disabled)
- socket_buffer (8192)
- socket_keepalive (false)
- recycle_timeout (0)
- connect_timeout (0)
- reply_timeout (0) 
- prepost_timeout (0)
- recovery_options (0)

>  server.xml
>   <!-- Define an AJP 1.3 Connector on port 8009 -->
> <Connector port="8009"
> enableLookups="false" redirectPort="8443" protocol="AJP/1.3" /> 

You should read documentation about attributes minSpareThreads,
maxSpareThreads and maxThreads and choose values according to your
apache
mpm settings.



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