[jboss-user] [Tomcat, HTTPD, Servlets & JSP] - Open connections with Apache 2.2+mod_proxy_ajp+JBoss/Tomcat

[skeumurian]

Hello,

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?

Thanks,
Stephen

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