Installation guide

https://access.redhat.com/knowledge/node/19932.
5. If Garbage collection is not responsible for the high CPU, use the thread dump
information gathered when validating CPU information to identify the threads.
One area that is not a direct consequence of an unoptimized mod_jk configuration but can still cause
issues with mod_jk is JVM and garbage collection related problems. When there are high pause times
and the JVM is not optimized for the app server, the pause times can cause mod_jk issues even when
mod_jk is tuned.
4.2. General Diagnostics
1. Verify the back end server is responsive by making a direct request to it.
2. Monitor high load using one of the following methods:
Twiddle
a. Locate the appropriate Twiddle script for your environment (twiddle.sh,
twiddle.bat or twiddle.jar) in the <JBOSS_HOME>/bin/ directory.
b. Run the following command:
<TWIDDLE> -u admin -p password get "jboss.web:name=ajp-
127.0.0.1-8009,type=ThreadPool"
DOCS NOTE: Is the twiddle command syntax the same for all versions of the
script? (excluding the file name itself)
Use the script appropriate to your operating system and environment .
Twiddle may need to be modified for each specific environment, but the above will
work in a default JBoss instance where no ports have been changed and JBoss is
starting on the localhost.
JMX Console
a. Navigate to http://localhost:8080/jmx-console.
b. Find the jboss.web section.
c. Click on name=ajp-localhost/127.0.0.1-8009,type=ThreadPool (or
whichever AJP ThreadPool matches your environment)
d. Investigate the currentThreadsBusy attribute. If this attribute is reaching the
maxThreads there will be a problem as JBoss Web is reaching the defined
ThreadPool capacity.
4.3. Getting Further Help
If none of the above information resolves your issue you can contact the Global Support Services staff
for assistance.
You can find the appropriate contact details at https://access.redhat.com/support/.
Please gather the following information prior to your call.
JBoss EAP boot.log.
Apache's httpd.conf and the httpd-mpm.conf file (if it exists).
mod_jk's workers.properties.
mod_jk's mod_jk.conf.
<JBOSS_HOME>/server/<PROFILE>/deploy/JBOSSWEB/server.xml
<JBOSS_HOME>/server/<PROFILE>/deploy/JBOSSWEB/META-INF/jboss-service.xml
The output of running httpd -V on Apache (httpd -V > httpd.out, for example).
Note the capital "V". A lowercase "v" will not produced the desired output.
Version of Apache htt pd or the JBoss Enterprise Web Server.
/etc/sysconfig/httpd
20 Chapter 4. Troubleshooting and optimizing mod_jk