Profiling application

You can profile local and remote Java applications using Java VisualVM.

Caution

For local applications it is easy because they are detected automatically and shown in the listing. For remote applications you need to do a little work.

Edit Tomcat startup scripts

Edit the $TOMCAT_HOME/bin/setenv.* files (setenv.sh for Linux and setenv.bat for Windows).

Note

The java.rmi.server.hostname should match the IP of the server, usually 127.0.0.1; replace it with the correct IP.

CATALINA_OPTS="$CATALINA_OPTS -Dcom.sun.management.jmxremote=true"
CATALINA_OPTS="$CATALINA_OPTS -Dcom.sun.management.jmxremote.port=9090"
CATALINA_OPTS="$CATALINA_OPTS -Dcom.sun.management.jmxremote.ssl=false"
CATALINA_OPTS="$CATALINA_OPTS -Dcom.sun.management.jmxremote.authenticate=false"
CATALINA_OPTS="$CATALINA_OPTS -Djava.rmi.server.hostname=127.0.0.1"

Caution

To connect to this remote Tomcat instance:

• Go to File > Add JMX Connection… and fill the hostname and port.
• You can also change the port to 9090 using the com.sun.management.jmxremote.port property.

Authentication

To enhance security, enable authentication. Edit the $TOMCAT_HOME/bin/setenv.* files (setenv.sh for Linux and setenv.bat for Windows).

CATALINA_OPTS="$CATALINA_OPTS -Dcom.sun.management.jmxremote.authenticate=true"
CATALINA_OPTS="$CATALINA_OPTS -Dcom.sun.management.jmxremote.password.file=$CATALINA_HOME/conf/jmxremote.password"
CATALINA_OPTS="$CATALINA_OPTS -Dcom.sun.management.jmxremote.access.file=$CATALINA_HOME/conf/jmxremote.access"

Edit the access control file $CATALINA_HOME/conf/jmxremote.access:

monitorRole readonly
controlRole readwrite

Caution

To show remote threads you need the readwrite permission.

Edit the password file $CATALINA_BASE/conf/jmxremote.password:

monitorRole tomcat
controlRole tomcat

Restrict access to these files:

$ chmod 600 $CATALINA_HOME/conf/jmxremote.access
$ chmod 600 $CATALINA_HOME/conf/jmxremote.password

Monitoring Remote JVM Over SSH

The easiest way to connect to the remote JMX is to use a SOCKS proxy.

$ ssh user@external.server.ip -D 8888

Configure VisualVM to use this proxy. Go to Tools > Options > Network and edit Manual Proxy Settings. Configure the SOCKS proxy at localhost and port 8888.

Now you can connect VisualVM to the remote target. Go to File > Add JMX Connection… and type the IP or hostname of the remote machine and the configured JMX port (in our sample configuration, 9090).

Note

More information at:

• Profiling With VisualVM, Part 1
• Profiling With VisualVM, Part 2
• Connecting Visual VM to Tomcat 7
• Monitoring and Managing Tomcat 7
• Remote Profiling of JBoss using VisualVM
• Troubleshooting application performance with VisualVM
• Monitoring of Tomcat with VisualVM and VisualGC
• Using VisualVM to fix live Tomcat and JVM problems

HPROF

Java includes HPROF, a profiler which collects application runtime information. HPROF is capable of presenting CPU usage, heap allocation statistics, and monitor contention profiles.

For example, it can collect CPU usage information by sampling threads.

Edit the $TOMCAT_HOME/bin/setenv.sh file (or setenv.bat if using Windows):

CATALINA_OPTS="$CATALINA_OPTS -agentlib:hprof=cpu=samples"

Note

When Tomcat starts you can see a file called java.hprof.txt. The CPU profiling info will be dumped to this file once the Tomcat process is stopped.

More information at:

• HPROF: A Heap/CPU Profiling Tool in J2SE 5.0
• HPjmeter