apache mod_proxy_balancer randomly stops sending traffic to backend server, but no errors

Question

I am using mod_proxy_balancer to load balance two back-end IIS servers. When monitoring the balancer-manager gui, I noticed that occasionally apache will stop sending traffic to one of the members. However, there are no errors present in the logs, and nothing to indicate that the server is unavailable. I have tried various lbmethods (bytraffic, bybusyness) and see the same result. I need to determine why traffic stops going to a member that is seemingly in good health and not returning errors. This generally happens under heavy load, which results in performance issues as one server is handling all requests.

Relevant config:

<Proxy balancer://cluster1>
    BalancerMember http://iis1:80 route=2 timeout=45 keepAlive=On
    BalancerMember http://iis2:80 route=1 timeout=45 keepAlive=On
    ProxySet stickysession=ROUTEID
</Proxy>

Answer 1

Figured this out - it's because we are using sticky sessions on both our hardware load balancer and apache balancer configs. So when we run a load test using jMeter, all of the traffic goes to one server. I hope this helps.