httpd.conf:

LoadModule proxy_module /usr/lib/apache2/modules/mod_proxy.so
LoadModule proxy_http_module /usr/lib/apache2/modules/mod_proxy_http.so
LoadModule proxy_module /usr/lib/apache2/modules/mod_proxy_ajp.so
LoadModule proxy_http_module /usr/lib/apache2/modules/mod_proxy_balancer.so
<Proxy balancer://testcluster stickysession=JSESSIONID>
BalancerMember ajp://localhost:8109 min=10 max=100 route=server1 loadfactor=1
BalancerMember ajp://localhost:8209 min=20 max=200 route=server2 loadfactor=1
</Proxy>
ProxyPass / balancer://testcluster/

[Fri Feb 27 16:45:44 2015] [notice] Apache/2.2.22 (Ubuntu) configured -- resuming normal operations
[Fri Feb 27 16:46:48 2015] [warn] proxy: No protocol handler was valid for the URL /. If you are using a DSO version of mod_proxy, make sure the proxy submodules are included in the configuration using LoadModule.