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From Rainer Jung <>
Subject Re: Problem with AJP connector
Date Thu, 25 Sep 2008 08:10:31 GMT
Woytasik Joe wrote:
> We are running IIS6 and Tomcat 6, with the AJP connector forwarding
> traffic from IIS to Tomcat.  Everything has been working well until we
> started running some load tests.  When we ramp up our testing we start
> to see the following errors in the connector log.
> [Wed Sep 24 14:28:42 2008] [3456:1504] [error] jk_ajp_common.c (1879):
> (IppsClaimsWorker) Connecting to tomcat failed. Tomcat is probably not
> started or is listening on the wrong port
> [Wed Sep 24 14:28:42 2008] [3456:1504] [error] jk_isapi_plugin.c (1082):
> service() failed
> What could be causing this issue?  Any help or troubleshooting tips
> would be appreciated.

1) Use netstat to find out, how many connections from the isapi plugin 
of IIS to Tomcat are in use. Those map to the number of parallel 
requests allowed. Also check, if you yourself can connect to the AJP 
port, e.g. with "telnet".

2) Do a couple of Java thread dumps (not: memory dumps) for your Tomcat 
and have a look, what they are doing and if this fits your expectation.

3) Check the number of threads configured for your AJP connector. This 
is again the maximum concurrency in requests allowed. Don't go to far. 
If a backend, like a database gets to slow, your throughput goes down 
and new requests will get in trouble. It doesn't make sense to try to 
queue those by using an excessive number of threads.



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