This chapter contains the frequently asked questions and answers about Java Mission Control.
This section includes the following topics:
This topic lists and provides answers to frequently asked questions about Java Mission Control.
I cannot connect the JMC Client to the JVM. What could be the problem?
I'm getting exceptions during startup about classes not being found. What is wrong?
Consider the following:
Are you using the correct protocol?
Ensure that you are using the same version of the Java JVM that you want to monitor as is being used by the Java JVM running the JMC client.
The format of the service URL is:
service:jmx:rmi:///jndi/rmi://<hostname>/jmxrmi
Are the correct ports opened?
Note that running JMX over RMI requires two ports and that one of the ports will not be known beforehand.
Is the communication caught in a firewall?
For more information, see "Java Mission Control Communications" in the Introduction to Java Mission Control on the Oracle Technology Network.
Sometimes RMI can have a problem determining which address to use. This can happen because of any of the following:
There are access restrictions in the Security manager.
The machine is multihomed and RMI is selecting the wrong interface.
There is a misconfigured hosts file or a number of different network related configuration problems.
If all else fails, you can try specifying the java.rmi.server.hostname
system property. Note that this can affect applications running in the Java JVM.
Ensure that you are using JAVA_HOME/bin/jmc
to start the JMC client.
Ensure that you are using JAVA_HOME/bin/jmc
to start the JMC client. Make sure that there is a directory named hsperfdata_
USER in your tmp
directory, where USER is your login name. Make sure that the user has write permissions for this directory. Also make sure that you are using a file system that supports access control lists (ACLs).
If you have any questions or any suggestions about how to improve the Java Mission Control plug-ins, share them in the Java Mission Control forum, which is monitored by the Mission Control engineering team. To access the news group, go to:
https://forums.oracle.com/forums/forum.jspa?forumID=1419