Intermittent error when using mod_proxy to do reverse proxy to SOAP service

Solution 1:

In case someone else runs into this. This is a bug in mod_proxy that can be avoided by putting these lines in your httpd.conf:

SetEnv force-proxy-request-1.0 1
SetEnv proxy-nokeepalive 1

https://issues.apache.org/bugzilla/show_bug.cgi?id=37770

For info on what these variables do see the mod_proxy documentation. They have a specific section, Protocol Adjustment, that addresses these variables.

Solution 2:

Take note of the Apache documentation here: http://httpd.apache.org/docs/2.2/mod/mod_proxy_http.html

It seems there is a race condition in mod_proxy_http, but it can be avoided by including:

SetEnv proxy-initial-not-pooled 1

Which prevents Apache using a pooled connection if this is an initial request.

The document does note that this setting will give a performance downgrade.