Bad Gateway 502 error with Apache mod_proxy and Tomcat

Question

We\'re running a web app on Tomcat 6 and Apache mod_proxy 2.2.3. Seeing a lot of 502 errors like this:

Bad Gateway! The proxy server received an in

Answer 1

So, answering my own question here. We ultimately determined that we were seeing 502 and 503 errors in the load balancer due to Tomcat threads timing out. In the short term we increased the timeout. In the longer term, we fixed the app problems that were causing the timeouts in the first place. Why Tomcat timeouts were being perceived as 502 and 503 errors at the load balancer is still a bit of a mystery.