Sometimes it can be useful to monitor performance of Java Virtual Machine (VM) on remote host. To do so, a very nice tool – VisualVM – can be used. It can be run on local host and get information from jstatd running on a remote host. In addition, VisualVM comes with a number of useful plugins. This blog describes how to run VisualVM with VisualGC, which is Visual Garbage Collection Monitoring Tool to monitor Tomcat on remote machine. However, the solution can be also applied to other applications running on JavaVM.
Add the following options to
CATALINA_OPTS variable to enable JMX support in Apache Tomcat.
in my case:
You can find more information about Monitoring and Managing Tomcat here: Monitoring and Managing Tomcat
We want to monitor Tomcat instance running on remote machine. To check whether it is running use:
The above command run on my remote machine returns the following:
Notice that pid is ’28743′.
To get JavaVM process status you can run
jps command, which is Java Virtual Machine Process Status Tool.
jps is located is your
Java JDK HOME/bin directory. Description of
jps command can be found here. Note that
jps returns only Java processes run by the user, who runs
jps. To get list of all Java processes run
sudo jps. See examples below.
jps run on my remote machine:
sudo jps run on my remote machine:
Notice that lvmid for Tomcat (in this case – Bootstrap) is ’28743′ which is the same as pid.
to check the host name, e.g.,
Make sure that in
/etc/hosts file this hostname has IP by which it is visible to the machine that will be running VisualVM (local machine), e.g.,
Run jstat Deamon
jstatd, which is jstat Daemon can be found in
Java JDK HOME/bin. As described in documentation to jstatd, which can be found here: , create a file called jstatd.policy in any directory you choose, e.g., /home/joanna. The file should contain the following text:
Run jstatd using the following command. Make sure you run it with root permissions.
You can add the following flag to log the calls and see what is going on:
Check access to jstatd
in my case
You should see the same output as for
sudo jps running on remote machine.
jvisualvm can be located in your
Java JDK HOME/bin directory also it can be downloaded from here: JVM download
and install the plugins you require including VisualGC plugin. My selection is presented in the screen shot below.
Add remote host – one that
jstatd is running on.
give IP of the host, e.g., 126.96.36.199. The same IP should be set for the host name in
/etc/hosts on remote server.
Now you should be able to access the Java processes running on remote host including Tomcat as presented below.
All tabs including VisualGC on right hand site should now show appropriate graphs. See sample screen shot below: