Apache 2.2.3 prefork mpm mod_proxy_ajp

["c." <chris.huisman@xxxxxxxxx>]

Hello,

I'm having a problem with mod_proxy_ajp, I am receiving the following error messages:

[Fri Mar 16 11:37:37 2007] [error] ajp_check_msg_header() got bad signature 420
[Fri Mar 16 11:37:37 2007] [error] ajp_ilink_receive() received bad header
[Fri Mar 16 11:37:37 2007] [error] ajp_read_header: ajp_ilink_receive failed
[Fri Mar 16 11:37:37 2007] [error] (120007)APR does not understand this error code: proxy: read response failed from xxx.xxx.xxx.xxx:8009 (
xxx.xxx.xxx.xxx)
[Fri Mar 16 13:28:45 2007] [error] (70007)The timeout specified has expired: ajp_ilink_receive() can't receive header
[Fri Mar 16 13:28:45 2007] [error] ajp_read_header: ajp_ilink_receive failed
[Fri Mar 16 13:28:45 2007] [error] (120006)APR does not understand this error code: proxy: read response failed from xxx.xxx.xxx.xxx:8009 (xxx.xxx.xxx.xxx)

in my apache error log.  

The following are my configuration files:

httpd.conf:

...
Timeout 300

KeepAlive On

MaxKeepAliveRequests 0
KeepAliveTimeout 15

<IfModule prefork.c>
StartServers 8
MinSpareServers 10
MaxSpareServers 25
ServerLimit 256
MaxClients 256
MaxRequestsPerChild 4000
</IfModule>

<VirtualHost xxx.xxx.xxx.xxx:80>
        ServerAdmin webadmin@xxxxxxx
        DocumentRoot /var/www/html
        ServerName www.xxx.com
        ServerAlias www.xxx.ca www.xxx.biz xxx.com 
xxx.ca xxx.biz
        ProxyPreserveHost On
        ProxyRequests Off

        Redirect 301 /cgi-bin/edd.cgi http://www.xxx.com/order/product.html
        Redirect 301 /cgi-bin/menu.cgi http://www.xxx.com/order/product.html

</VirtualHost>


In my tomcat server.xml, I have:

    <!-- Define an AJP 
1.3 Connector on port 8009 -->
    <Connector address="xxx.xxx.xxx.xxx"
               port="8009"
               enableLookups="false"
               protocol="AJP/1.3"
               minSpareThreads="20"
               maxSpareThreads="200"
               maxThreads="1024"
               connectionTimeout="600000"
     />

and my proxy_ajp.conf: 

ProxyPass /order ajp://xxx.xxx.xxx.xxx:8009/order
ProxyPass /dwr ajp://xxx.xxx.xxx.xxx:8009/dwr

The error messages come up intermittently maybe 5 times a day (although the ajp_check_msg_header() is a new one).  I believe what happens is the user gets to the secure checkout page, hits the order button and then the error shows up in the log file, but what the user gets is a blank page instead of the order confirmation page. 

I've been through the mailing lists and seen some advice for people who are using the worker mpm, but nothing when using prefork.

Can anyone please, let me know what is going on (I'd like to understand why I get the error messages) and what to do prevent the error from coming up.

Thanks all for your consideration it is appreciated,

Chris.