Apache httpd mod_proxy errors

[ljohnson]

Hi folks

We have three identical webapps running over Tomcat and we are load balancing user connections across the three Tomcat instances via Apache mod_proxy.

The setup works, however we are experiencing frequent (although not regular\consistent) proxy errors.

The error displayed to the end user is:

Proxy Error 
The proxy server received an invalid response from an upstream server.
The proxy server could not handle the request GET /webapp/. 
Reason: Error reading from remote server

The apache error log file contains many errors like:

[Mon Dec 10 15:40:16 2007] [error] [client 149.193.26.147] proxy: Error reading from remote server returned by /webtop/webtop/classic/classic.jsp, referer: http://myserver.com/webtop/component/main?__dmfClientId=1194294213076&__dmfRequestId=__client1~~2&__dmfJumpType=jump
[Mon Dec 10 15:40:46 2007] [error] [client 172.17.240.212] proxy: error reading status line from remote server myserver.com
[Mon Dec 10 15:40:46 2007] [error] [client 172.17.240.212] proxy: Error reading from remote server returned by /webtop/com/documentum/ucf/server/transport/impl/GAIRConnector
[Mon Dec 10 15:42:44 2007] [error] [client 149.193.36.88] proxy: error reading status line from remote server myserver.com, referer: http://myserver.com/webtop/webcomponent/library/searchresultslist/searchex/wait.jsp?__dmfRequestId=__client11~~9&queryType=queryId&drilldown=false&type=technical_doc&showwait=true&queryId=187&Reload=1197286664036&__dmfClientId=1197286133256
[Mon Dec 10 15:42:44 2007] [error] [client 149.193.36.88] proxy: Error reading from remote server returned by /webtop/webcomponent/library/searchresultslist/searchex/wait.jsp, referer: http://myserver.com/webtop/webcomponent/library/searchresultslist/searchex/wait.jsp?__dmfRequestId=__client11~~9&queryType=queryId&drilldown=false&type=technical_doc&showwait=true&queryId=187&Reload=1197286664036&__dmfClientId=1197286133256
[Mon Dec 10 15:44:27 2007] [error] [client 149.193.111.96] proxy: error reading status line from remote server myserver.com, referer: http://myserver.com/webtop/custom/jsp/navigation/doclist/objectlist.jsp
[Mon Dec 10 15:44:27 2007] [error] [client 149.193.111.96] proxy: Error reading from remote server returned by /webtop/webcomponent/library/searchresultslist/searchex/wait.jsp, referer: http://myserver.com/webtop/custom/jsp/navigation/doclist/objectlist.jsp
[Mon Dec 10 15:49:09 2007] [error] [client 149.193.40.245] proxy: error reading status line from remote server myserver.com, referer: http://myserver.com/da/webcomponent/library/searchresultslist/searchex/wait.jsp?__dmfRequestId=__client11~~4&queryType=queryId&drilldown=false&type=dm_sysobject&showwait=true&queryId=2&Reload=1197287048791&__dmfClientId=1197286607081
[Mon Dec 10 15:49:09 2007] [error] [client 149.193.40.245] proxy: Error reading from remote server returned by /da/webcomponent/library/searchresultslist/searchex/wait.jsp, referer: http://myserver.com/da/webcomponent/library/searchresultslist/searchex/wait.jsp?__dmfRequestId=__client11~~4&queryType=queryId&drilldown=false&type=dm_sysobject&showwait=true&queryId=2&Reload=1197287048791&__dmfClientId=1197286607081

I wondered if this could be due to a bug within the Apache software (e.g bug 37770).

Can anyone advise on this?

We are running Apache 2.2.4

Many thanks

[shri]

Do you have logs with at debug level?

What are your balancer setups like?

I'll try and grep through the source code to see where the error happens (I suspect it happens due to a socket error).

[shri]

And what are the corresponding responses from the app server?