Hi,
you should try to telnet tomcat server from web server.
telnet <host> <port>
If the telnet is successful, you need to check configuration of mod_proxy_ajp.
If the telnet will be not successful, you have network problem.
mh
Sent from my iPhone
On 17.9.2010, at 18:18, Shantanu Pavgi <pa...@uab.edu> wrote:
> Hi,
>
> I have a Apache http server and a Tomcat server configured using AJP
> connector (mod_proxy_ajp). The http server serves HTML/PHP pages and also
> proxies Java webapp requests to back-end Tomcat server.
> System config:
> * Both servers are running as Virtual Machines
> * CentOS 5.4
> * Apache Tomcat 6.0.26 and Sun JDK 1.6
> * Apache http: 2.2.3 (it's old, but that's what comes with default CentOS
> repo)
>
> We are getting HTTP 500/503 errors quite frequently, but they appear to be
> random in nature and hence difficult to debug. I have tried increasing
> following config parameters, but it didn't help:
> * On http server: max and smax connections in proxy_ajp.conf
> * On Tomcat server: maxThreads and maxSpareThreads in Tomcat's server.xml
>
> Following logs were seen on both sides:
> == Apache http server ==
> * In browser: 500/503 - internal server error.
> * In Apache logs at debug mode - same logs for 500 and 503 error:
> {{{
> [Wed Sep 15 22:50:09 2010] [debug] ajp_header.c(430): ajp_marshal_into_msgb:
> Done
> [Wed Sep 15 22:50:09 2010] [debug] mod_proxy_ajp.c(239): proxy:
> APR_BUCKET_IS_EOS
> [Wed Sep 15 22:50:09 2010] [debug] mod_proxy_ajp.c(244): proxy: data to read
> (max 8186 at 4)
> [Wed Sep 15 22:50:09 2010] [debug] mod_proxy_ajp.c(259): proxy: got 0 bytes
> of data
> [Wed Sep 15 22:50:09 2010] [error] ajp_read_header: ajp_ilink_receive failed
> [Wed Sep 15 22:50:09 2010] [error] (120006)APR does not understand this error
> code: proxy: read response failed from 10.0.0.10:9080 (tomcat.lab.uab.edu)
> [Wed Sep 15 22:50:09 2010] [debug] proxy_util.c(2062): proxy: AJP: has
> released connection for (tomcat.lab.uab.edu)
> [Wed Sep 15 22:50:09 2010] [debug] ssl_engine_kernel.c(1765): OpenSSL: Write:
> SSL negotiation finished successfully
> [Wed Sep 15 22:50:09 2010] [info] [client 10.0.0.8] Connection closed to
> child 3 with standard shutdown (server httpd.lab.uab.edu:443)
> }}}
> * tcpdump on Apache http server: Shows a packet going out to Tomcat server
>
> == Tomcat server ==
> * In Tomcat logs catalina.out: No logs
> * In Tomcat access logs catalina.out: No logs
> * tcpdump on Tomcat: No incoming packet seen
>
> The request doen't seem to reach Tomcat at all. I have checked syslog
> (/var/log/messages), but I don't see any dropped packet logs as well.
>
> Anyone else had this issues before? Any pointers on how to debugs this would
> be really helpful.
>
> Thanks,
> Shantanu Pavgi.
>
