Hi all,

when using "mod_proxy_ajp" of Apache2 2.2.16 in combination with two Apache
Tomcat 6.0.29 servlet containers, we often see the following entries within the
Apache2 error log of the virtual host:

[Thu Nov 25 16:17:26 2010] [error] ajp_read_header: ajp_ilink_receive failed
[Thu Nov 25 16:17:26 2010] [error] (120006)APR does not understand this error 
code: proxy: read response failed from 10.35.32.241:8009 
(rb-wcmstc2.de.bosch.com)
[Thu Nov 25 16:17:26 2010] [error] [client 10.35.32.123] proxy: error 
processing end, referer: 
https://xxx.dot.com/<context_root>/workflow/dialoges/tasks3.jsp?refresh=1

When looking in the central Apache2 error log, we see:
[Thu Nov 25 16:17:26 2010] [error] (70007)The timeout specified has expired: 
ajp_ilink_receive() can't receive header

Additionally, we sporadically see connection switches from one Tomcat
to the other without any understandable reasson (here from "rb-wcmstc2" to 
"rb-wcmstc1"):

10.35.32.123 - - [25/Nov/2010:16:17:31 +0100] "POST 
/servlet/ClientIO/5cmxicinliar/s6/234 HTTP/1.1" 500 1255 "-" "Jakarta 
Commons-HttpClient/3.1" "
JSESSIONID=68BE78C5C6A2B9756CED86543095C221.rb-wcmstc2" 
"68BE78C5C6A2B9756CED86543095C221.rb-wcmstc2" 
"JSESSIONID=C9F5C78771552AF9C15F1D0064099948.
rb-wcmstc1; Path=/" 4784

Might the below timeout be set to short (in combination with the aboe "timeout" 
error log entry)?

The current "mod_proxy_ajp" configuration looks like this:

<Proxy balancer://fs4server>
        # One tomcat node has been outcommented due to the following ticket: 
Help-20100510-651
        BalancerMember ajp://rb-wcmstc1.xxx.dot.com:8009 loadfactor=100 
retry=10 route=rb-wcmstc1
        BalancerMember ajp://rb-wcmstc2.xxx.dot.com:8009 loadfactor=100 
retry=10 route=rb-wcmstc2

        ProxySet stickysession=JSESSIONID|jsessionid
        ProxySet lbmethod=byrequests
        ProxySet scolonpathdelim=On
        #ProxySet nofailover=On
        ProxySet timeout=45
</Proxy>

Or is there a bug available within the "mod_proxy_ajp" module of Apache2 
(details see: http://www.mail-archive.com/us...@tomcat.apache.org/msg84118.html)
Should we switch to "mod_proxy_http"?


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