I've been trying to track down a problem on our server for a while now and thought I'd check in here to see if anyone has a solution. I have Apache 2.2.2 setup as a front end for JBoss 4.0.2 on the same server. I have a rather long list of named virtual hosts being served on this one system. I'm using mod_proxy_ajp to route traffic to multiple web applications on the server. I'm running into a situation where the number of connections from Apache to the Tomcat AJP connector (localhost:8009) is forever growing and eventually people are blocked from accessing the server. The connections are left in the "ESTABLISHED" state as viewed by netstat.
tcp4 0 0 localhost.8009 localhost.49163 ESTABLISHED tcp4 0 0 localhost.49163 localhost.8009 ESTABLISHED
I've tried using Apache with the worker MPM as well as the pre-fork MPM and the problem seems to occur with both, but becomes a problem a lot sooner with the pre-fork MPM.
I tried editing jboss-4.0.2/server/default/deploy/jbossweb-tomcat55.sar/server.xml to include a connectionTimeout value of 20000 milliseconds. This timeout works, but then instead of the connections being left in the "ESTABLISHED" state they are now left as "CLOSE_WAIT." I've tried changing various values on the Apache side, such as specifying smax, ttl, etc. to no avail.
I'm defining the proxy to my application like this:
<Location /cdf> ProxyPass ajp://localhost:8009/cdf smax=30 ttl=30 retry=1 ProxyPassReverse ajp://localhost:8009/cdf </Location>
This is included in each named virtual host that needs access to the application. Other virtual hosts have their own Location entries that proxy pass to other applications.
My http-mpm.conf is setup like this for the worker MPM:
<IfModule mpm_worker_module> StartServers 2 MaxClients 300 MinSpareThreads 25 MaxSpareThreads 300 ThreadsPerChild 25 MaxRequestsPerChild 0 </IfModule>
and like this for the prefork:
<IfModule mpm_prefork_module> StartServers 15 MinSpareServers 51 MaxSpareServers 65 MaxClients 500 MaxRequestsPerChild 0 </IfModule>
I have a test server that I has a simpler version of the same setup on (no named virtual hosts) and I'm seeing this behavior there as well. I've tried creating a test application that only includes a basic index.html and it appears to behave the same way. Am I missing something? Am I using mod_proxy_ajp incorrectly?