I am in the midst of performance testing a web application and I get these errors in EWS logs

[Sat Apr 18 03:01:01 2015] [error] [client xx.xx.xxx.253] proxy: DNS lookup failure for: jboss-host-name returned by /some/url, referer: http://f5hostname/context/URI

It occurs only at high load levels. I have seen posts where this error occurs due to incorrect proxy configuration, but my case doesn't fall under that I guess. At the very end of the test I get another error - "All workers are in error state". I think the first DNS error causes all workers to shutdown.

Can someone point where I could start looking? Please let me know if you need more details than whats mentioned below.

More details:

Apache version: 2.2

mod_cluster: 1.2.4.Final

I have an F5 in front of two EWS. There are ten JBoss EAP6.1 servers in the balancer.

Apache configuration snippet: (I am not using proxypass directive, just modcluster)

<IfModule mod_proxy.c> ProxyRequests Off ProxyVia On </IfModule>  

<IfModule mpm_worker_module> ServerLimit, StartServers and worker related attributes configured here </IfModule>  

ProxyPreserveHost On 

MemManagerFile /var/cache/httpd  

<VirtualHost *:1280> 

     ManagerBalancerName some2 (this is the same used in jboss using proxylist) ........

Apache Logs:

[Tue Apr 21 22:06:25 2015] [debug] mod_proxy_http.c(1973): proxy: HTTP: serving URL http://jbosshost:8080/uri

[Tue Apr 21 22:06:25 2015] [debug] proxy_util.c(2011): proxy: HTTP: has acquired connection for (jbosshost)

[Tue Apr 21 22:06:25 2015] [debug] proxy_util.c(2067): proxy: connecting http://jbosshost:8080/uri

[Tue Apr 21 22:06:25 2015] [error] [client 10.xxx.xxx.xxx] proxy: DNS lookup failure for: jbosshost returned by /URI

[Tue Apr 21 22:06:25 2015] [debug] proxy_util.c(2029): proxy: HTTP: has released connection for (jbosshost)

OS:

RHEL 6.5