Installation guide

Common Errors
"cping/cpong" Errors
Presents with errors like the following:
[info] ajp_handle_cping_cpong::jk_ajp_common.c (865): timeout in reply
cpong
...
[error] ajp_connect_to_endpoint::jk_ajp_common.c (957): (nodeA)
cping/cpong after connecting to the backend server failed (errno=110)
[error] ajp_send_request::jk_ajp_common.c (1507): (nodeA) connecting to
backend failed. Tomcat is probably not started or is listening on the
wrong port (errno=110)
These cping/cpong messages do not indicate a problem with mod_jk at all, they indicate that
JBoss did not respond in the defined cping/cpong time.
This is seen many times when there is high load on the JVM JBoss is running on causing high
garbage collection or potentially thread contention. It could also be that the JBoss instance is
overloaded, or even that a firewall is blocking the connection or there are network issues.
The following workflow may assist to correct these type of issues:
Procedure 4.1. Resolving "cping/cpong" Errors
1. Optimize your Apache and JBoss configuration. You can contact Red Hat's Global
Support Services for assistance with this.
If this does not resolve the issue, proceed to St ep 2
2. Confirm that there is no firewall blocking or dropping the AJP connections.
"T omcat is down" Errors
Presents with errors like the following:
1. [error] ajp_get_reply::jk_ajp_common.c (2020): (node1) Timeout with
waiting reply from tomcat. Tomcat is down, stopped or network
problems (errno=110)
The above error means that JBoss did not respond in the configured reply_timeout time.
The solution can be one (or both) of the following:
a. Increase the reply_timeout.
b. Verify there are no garbage collection issues/long pause times in JBoss that may
prevent the request from responding thus causing that error.
2. [Fri May 25 11:53:37 2012][11159:3086420192] [debug]
init_ws_service::mod_jk.c (977): Service protocol=HTTP/1.1
method=POST ssl=false host=(null) addr=127.0.0.1 name=localhost
port=80 auth=(null) user=(null) laddr=127.0.0.1 raddr=127.0.0.1
uri=/foo/bar
...
[Fri May 25 11:58:39 2012][11159:3086420192] [debug]
jk_shutdown_socket::jk_connect.c (681): About to shutdown socket 17
[Fri May 25 11:58:39 2012][11159:3086420192] [debug]
jk_shutdown_socket::jk_connect.c (689): Failed sending SHUT_WR for
socket 17
[Fri May 25 11:58:39 2012][11159:3086420192] [info]
ajp_connection_tcp_get_message::jk_ajp_common.c (1150): (node1) can
not receive the response header message from tomcat, network
problems or tomcat (127.0.0.1:8009) is down (errno=104)
[Fri May 25 11:58:39 2012][11159:3086420192] [error]
ajp_get_reply::jk_ajp_common.c (1962): (node1) Tomcat is down or
refused connection. No response has been sent to the client (yet)
The above error likely means that JBoss did not respond in the configured core Apache
Timeout.
Note that with these messages the [11159:3086420192] portion of the message
serves as an identifier for the connection/request in question. Therefore tracing back
from the point of the error in logs can help clarify the activity around the
connection/request that lead to the error.
In this case, that helps clarify that the error was experienced five minutes after the
response was sent to JBoss, which likely points to a five minute timeout (this is Apache's
Timeout directive default if not specified). If the T imeout is interrupting mod_jk requests,
then it should be increased from the current value to allow for the maximum acceptable
response time.
Procedure 4.2. Resolving "T omcat is down" Errors
a. Optimize your Apache and JBoss configuration. You can contact Red Hat's Global
Support Services for assistance with this.
JBoss Enterprise Application Platform 5 HTTP Connectors Load Balancing Guide 17